Backloading adc damage

Currently, an adc will deal the same damage per shot, only variable being crit chance. They are supposed to counter tanks by being the only one capable of killing them efficiently. They do this with giant amounts of raw damage and then % armor penetration. They pay very little for the armorpen. This raw damage means that if they can kill a tank in 8 seconds, if the tank is five times as tanky than a squishy, the squishy will die in about 2 seconds.

This means the only role capable of surviving an adc (for significant time) is the role the adc is supposed to counter. An assassin can try and burst them, just as a mage if the adc is out of position, but they'd both die in 2 seconds if they somehow fail (counterplay is important in LoL).

My suggestion to change this is backloading the adc damage; make them still kill a tank in 8 seconds, but make them kill a squishy in 4 seconds (doubling their lifetime). I'd do this by replacing the critical chance, a burst stat, with, I'll call it critical strike.

This new stat, critical strike, would give an adc a stackable buff upon attacking an enemy champion that increases the damage your next attacks deal.

If you have 25% critical strike: Your first attack will deal 100% damage. Your second attack..125% Your third attack......150% Your fourth attack....175% And so on.

This stat means the adc maintains a status as lategame monstrous scaler, but they won't be an assassin of squishies anymore. It'd also make the tank counter anyone but the adc lategame and make the bursters mages and assassins, whose core identity it is anyway (certain mages' identity at least). Nothing changes for the fighter, whose gameplay pattern in a teamfight stays vague.

Whether the crit strike buff interacts somehow with minions/monsters and how it acts when you switch targets is not very important right now. (I'd make non-champions maintain the stacks but not stack them and make you lose half the stacks upon attacking a different champion than your last.)

First time I started a thread on these fancy boards, I'm open for reorganization suggestions.

Tl;dr: Replace a core stat of adcs (crit chance in my suggestion) with a stat that backloads their damage, meaning instead of for example killing tanks in 8 seconds and squishies in 2 seconds, they'll kill tanks in 8 seconds and squishies in 4 seconds (doubling their lifetime).