Why don't marksmen have some kind of real gating on their damage like assassins are getting?

Marksmen auto and can do crits one after another resulting in thousands of damage in under 3 seconds which is the kind of thing assassins are getting nerfed to have limited. This in turn means marksmen can often kill assassins before the assassin can kill them at many parts of the game especially with even the smallest of CC or escape mechanic of a marksmen.

Why don't marksmen have some kind of wind up factor built in their kits making their up front burst a joke but their sustained DPS godly which is what they are suppose to be good for in a fight? We have some things like this in Fervor and rageblade in the game as examples of how it would work. Why is something like this not the limiting factor of a class that is getting it's counters limited?

Heck you even kinda see this in Jinx's kit with her Q getting more attack speed.