There was definitely enough time for you to react to my pings to back off. Maybe because I'm behind compared to my enemy and I could get picked off of very easily. Or because they're an assassin and I can't help at all besides pinging. Warding the river is very helpful too.
I would rather shove my lane to punish them for attempting a roam on bot/top.
If you can't follow always best to push your lane, sometimes enemies would just sit in brushes and wait for you to face check when they go MIA which isn't worth the risk at all.
Why didn't you follow your laner? Umm let me see because there's a 50/50 chance at guessing on what lane he/she is going. My ward ran out. Better mobility. I can follow, but 
will get there faster than 
. 
is ahead and will just attack me if I follow. 
has stealth and is currently stronger.
Sometimes the correct play is to follow your laner though. For example, your allies to react to your pings, but they're at their own turret and have nowhere else to go I would say you should've followed. There are also times where the absolutely worse thing to do is follow your laner. If you don't have wards everywhere and you try to follow a Cass, you're going to die.
"Because I don't have boots!" 
said.
I think it's hilarious when I get flamed when I get out-roamed by a TF or Taliyah post 6. Sure, let me just quantum tunnel down to botlane to save your sorry ass. I call out when my laner is 6 if they have amazing roaming potential. And ping MIAs then dangers if both of my lanes haven't backed off a bit into safety. If you live and they roamed for nothing, they lose a fair amount of XP and gold. And their tower gets fairly damaged.
If a fight breaks out near me then I'll go and assist, but if they're a full lane away and moving away from me, there is no point in me wasting my time on that. I'd rather say in lane, get gold, get EXP, and push to tower to deny the enemy laner both things while I also apply pressure on that tower to take it down easier later. People that think "You have to follow your laner when they leave" are bad at the game because it isn't always the best option to do so. Meanwhile if the situation was reversed they would be saying the same things as you about denying things.
I had this happen to me an ARURF where th enemy mid laner was a Nunu and I was Quinn.
Nunu left lane at level 2, I pinged, he appeared top and got a double. "Quinn is the best roamer in the game" was the response I got when I said I couldn't follow. I was a level 2 Quinn. No one is going to be able to keep up with a blood boil spam Nunu unless they have a speedup themselves.
This applies doubly to Talon and Leblanc and mobile assassins. Spoiler alert: If I'm Ziggs, I can't match a Talon's roam because he jumps over walls.
Or because they shoved and I chose to pick up the 10 farm that will give me a small advantage later on rather than just leave my lane and follow because you're not paying attention to enemy missing pings.
People don't understand that you DON'T have to follow your laner. You can actually get ahead by having your enemy laner waste time, cs, and exp by attempting to roam. All it takes is a team that respects your SS and pings and you will get the upper hand out of the enemy's choice to roam.
When my teammates don't respect my pings and blame me for not following my laner more than twice I just stop pinging SS. It's clearly useless, they don't respect it or even have enough awareness to look at the minimap. My laner probably walks through 3 wards, scuttle, and 10000 danger pings, and they STILL kill you.. then I guess there's no hope for you. Time to not even bother SSing anymore.
everytime i play a mage against an assasin i have to explain to my team that if i follow zed/talon he will just turn and probably just kill me or stay in a bush and wait for me to appear,so i just push the lane. Most of the times they dont complain since i ping danger on top of them a couple of times.
Reasons why your mid laner did not follow:
Given #4, a lot of people waste time trying to answer the enemy mid lane's roam. Unless you're playing TF, you shouldn't waste time running through river to try and counter roam. Instead, just push and get the turret.
I know this thread is a year old but I experoemced this bullshit in my recent ganes and I need to writr down some Frustration. I dont want tonportray a perfect player here. I also sometimes miss ss calls or I am sometimes brain dead but at least I qdmit my mistakes then. But how on Earth can you blame your midlaner when he just went base, called SS like 300 times, pinged to be careful bot side and you still die both. Some people even have Wards and can loterally see that someone is coming by themselves and there is still no reaction. Another situation: Youbgot 303947 wards in your jungle and tons of wards at dragon pit yet still the botlane somehow manages to oversee 4 people heading into botlane trying to dive them. How can ypu blame your midlaner for this. I am sick kf getfing blamed for other peoples mistake. It reached a point where I legit thought that these were potentially my mistakes but there is no way. Every Situation would have turnes out in my favour if the botlane would just back off. and let me push out my midlane. So I can also try to roam a bit.
Well you can actually follow using the safe path in your jungle if you got a control ward in there (and you should have one).
I have seen this excuse over the years so many times and I just wish people could understand, I can't always follow it. It's really that simple.
As a mid laner you gain a lot of advantage if that assassin wastes time roaming and you team punished them by avoiding the fight. If they don't get a fight, the fall so far behind. Let them waste their time, take the advantage they are literally handing to you. Roaming just removes that advantage and opens the door for the roaming (usually someone who NEEDS to get kills) to get ahead.
When people say that, what they're really complaining about is that you only pinged missing, you didn't tell/signal a lane they were incoming. In other words no one knows where they went(and sometimes people assume they backed or they're not coming to their lane because of that).
Why did you ping missing by the time I'm already dead
it's amazing how a losing mid laner can lose the game for everyone else
It's amazing how many times you can ping missing and careful, for the bot lane to flame you for pinging as they died to the roaming mid you have been pinging them about.
Just be aware if you don't follow your laner and your bot lane dies to a 2v4 tower dive you share some of the responsibly for that because you left them hanging and the risks for the enemy team in diving a 2v4 situation vs a 3v4 situation is very significant, and often times your presence alone can make them back off even if you are not super fed. If they do make that 2v4 dive and walk away with 2 kills, first turret and dragon then yeah you played a big role in letting them get such a lead as you afk farmed your lane.
If that's the case, is it then partly the bot lanes fault if the mid roams down to help and gets pinched in the Jung? Didn't think so. If they are fast pushing the lane and a dive is incoming, you need to leave, they made the play, don't give them more.
It's then on your mid and jungle to punish them by ganking top, trading towers, taking rift, counter jungling, etc. usually going down there is only delaying the inevitable.
Ever see the best players? they concede the tower and take other objectives, it's simply not worth it.
The funniest is when you ping "mia" because the enemy is recalling, then 2 minutes later he turns up bot and you get asked why didn't you follow. What am I supposed to do, stroll into their base to check where is he going?
