Toxicity towards supports feels like a low ELO thing
I rarely get it in +Plat, but whenever I make new accounts for fun holy Hell people can be toxic as fuck no matter how hard I am carrying them in lane. Their complete lack of understanding is cringe worthy as they ping me back over and over as I am last hitting minions with auto attacks when they are out of lane, helping them CS under turret when they lack AD/mechanics to do so early game, etc. I've had games where we completely stomped bot lane, then I go to roam to gank side lanes after tower is down and they die trying to 1 vs 2 because they are fed then go "wish I had a support" like it's my fault he walked up and tried to fight 2 people.
I only make new accounts to go into rank and rank them up because I make accounts for specific champions that I only play on that account. I am not trying to ruin low level games or anything, just to have fun, learn new characters or just have a dedicated account to my favorite champs.
I don't know, I think some of it is also dynamic que. I've had so many 4 man's harass me and troll me. One dynamic que was so upset I took one thing of wraiths from jungle to heal off of with Mordekasier that the jungle nunu came to my lane and ulted the wave and proceeded to do so for the rest of the game while they all harassed me in chat. Doing wraiths as Morde gives you a huge heal with your W because it heals more off jungle camps than it does off regular minions.
Don't get me wrong, plenty of assholes in Plat and Diamond and up, but those people have enough of an understanding to the game they don't harass you for these things.