Champions with non windowed offense are an issue
Champions like Vayne, Jax, Yasuo* Mundo, Cho'Gath etc. Who do not have a reasonable window on their offense are an issue. There are more than this but not many.
When you look at most carries, especially recent ones, just about all of them have a condition to unlock it or have a meaningful cooldown on it. Fiora has to hit vitals, Darius has to stack his passive, etc. Most marksman have cooldowns on their button steroids that matter quite a lot.
The champions I've listed above do not have that. Most of them have either completely passive damage steroids that are always on, or have cooldown that is negligible enough to not really be considered. Mundo and Cho'Gath have button tap steroids that get to 100% up time later on. Vayne is mostly only as limited by how many times she can attack one person. Jax has no meaningful gating to his offense, only his defense. And so on.
Essentially these champions tip fights in their favor by virtue of just existing. Their win condition is simply to outlast or deny your power ups; they have all of the counter play tools for you in their hand but you are not given the same courtesy. This is IMO a frustration point that isn't talked about enough. Its an interaction that does not fit into the current League philosophy and is one I think strongly deserves to be looked at.
* I'm tempted to give Yasuo a pass because while his direct damage may not have a real limit, he is at least conditioned on needing minion waves or a knockup to reliably close a gap.
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