User blog comment:Nearthel/Critical Strike and Penetrations overhaul/@comment-5266525-20150620182331/@comment-5266525-20150621101845

"The problem with critical strikes right now is that you can win or lose a trade just because of a lucky crit, while everything else in the game is consistent."

This is 90% of the time the first argument that anti-crit parties will give, and it's problematic for one reason:

Crits almost never factor into early trading because it is never purchased early or supplied with runes.

Why? Because it is unreliable for trading and it only helps with you with trading at that, not lasthitting or tower pushing. The only exceptions to that might be ADCs that rush Trinity but even they will prefer going Sheen and Phage over Zeal first and they're probably going to win a trade with a build like that regardless of whether they crit or not.

The only other point in the game where crits can make a big difference is endgame when ADCs are full build and can chunk each other for half-health in a single shot, but those situations are very, very rare.

I'm not arguing it is not a problem, but I am arguing that it's simply not big enough a problem to be worth giving the system a complete upheaval because of edge cases.