You read his idea and then you started commenting on the numbers which isn't relevant to the idea itself.
They absolutely are relevant, becasue the numbers determine what the system actually ends up doing. Is it intended to represent a potential increase in damage after fighting for long enough? Or is it meant solely to be a gate on early damage in a fight? Numbers are the factor that determines that.
Besides, 3/5 of my post had nothing to do with numbers. I criticized the design of making crit attack speed based, and I maintain those criticism.
without really changing the play style of marksmen since they will still be basic attacking from range like always
No, as I made a point of, it's a significant change in playstyle, because it encourages autoattacking the same target once you've built up stacks on them. There are carries who very much don't want to do that. Mobile, bursty carries are encouraged to switch targets based on openings in the fight, but this discourages and punishes that. Assassin type carries are supposed to threaten the backlines, which harder if your first attacks are strictly weaker. It also encourages attack speed based builds, because AD focused crit builds will suck dick from not being able to stack fast enough to make crit worthwhile.
If you want something that doesn't change playstyles, then it's very, very simple: %damage increase to autoattacks. Mathematically the same expected dps, and doesn't favor anybody. It's better than OP's proposal.
and no this doesn't make armorpen builds the new standard crit would still result in higher dps
If the first 3 autoattacks of a fight are strictly weaker than they are on live, then it absolutely will put pressure on carries to use armor penetration builds. It doesn't matter if it eventually builds up to slightly superior dps if it is strictly weaker every time you attack a new target. Ability focused builds are already only slightly off of being the norm for a lot of AD carries. This could easily push them over the edge.
It might even lead to more viable build options as well since you could just sit on that one infinity edge and still use it to amp up your dps big time whilst leaving room to buy different attack speed and ad items you would otherwise not really build
This is just so wrong. I have so many criticisms of this one sentence. It makes so many bad assumptions.
There is not a single reason to believe that a playstyle restriction would open up item options. There has never been a point in league's history where restrictions on playstyles opened up options. The game's design disallows that.
Let's enumerate why. First, sitting on one crit item will be worse than before, not better. If you're required to build stacks on enemies in order to make crit effective, then the last thing you want to do is go for low attack speed builds, but high attack speed requires that you buy crit. I'm not going to buy an attack speed reliant dps steroid without actually buying attack speed, and that requires buying more crit.
Second, what "different attack speed and ad items" are you thinking of? For attack speed, are you thinking of zeal items? Because, if you are, you can already stack those. The only other ones are BotRK and Wit's End, and these changes aren't making them any less crappy/situational. As for AD items, you'd still pick those up third or fourth, just like you do now. The only difference is that you won't possibly get them second in any situation because you NEED attack speed to make your early crit effective. All this does is limit a potential option.
I seriously don't think you thought about the items at all when you said that.
Third, there is nothing new about crit being a dps amp. Crit already is a DPS amp. That is explicitly its purpose. 20% crit is a 20% boost to dps. And yet, you don't see people sitting on one crit item on live, because it's mathematically inefficient. If you're looking to maximize dps, then there is a mathematical forumla for how much crit is needed. Having a ramp up doesn't change that. It doesn't make it any more rewarding to sit on one crit item. Maximizing dps will still require multiple items, particularly since all the attack speed items that are viable for a carry to purchase have crit.
Why do you think this would open up build options? Do you have a reason? Are you just thinking that because it's a change, it would open up more options? What's your justification?