They cant ever put this in because this isnt WoW, all these things differ depending on the monster that you fight as they have for years.

Damage done? yep
Accuracy? Yep
Critical Hit Rate? Yep
Parry? Yep
Shield Block? Yep

Go fight a level 1 and you'll see you'll block a whole lot and parry a lot, fight a level 50 and you do not. Everything depends on the stats and level of the monster you are fighting compared to your own stats.

There is no "If i add 2 accuracy i get 1% more hitrate", it doesnt work like that. Every stat you have compares to the monster it's stats. Get X amount of "Accuracy" more than the monster has "Evasion" and you cap out your hitrate.