Sometimes 5% or 10% aren’t the correct answers. Sometimes no number is the correct answer. Sometimes individual talents or skills need to be looked at to bring a spec in line in one aspect without harming them in another aspect.
If you just look at overall stastics over the course of a raid you’re mostly looking at ST or low target AoE, so if you hyper buff a spec like, say, WW monk without considering how it would affect their AoE in other aspects of the game, such as M+, then you’re left with a very broken game.