If crit encourages unpredictable gameplay and player decision making, why is it only present in bot?

>We think the game needs a certain amount of unpredictability in order to really test player decision-making in the heat of the moment, but there are ways to add unpredictability that aren't as RNG as crit.

This rings rather untrue with me, because crit is only ever really present on marksmen, who are, most of the time, only in bottom lane. Does this statement mean that top and mid lane don't really have any sort of unpredictability? I would argue that they do, and are far better at rewarding decision making than bot lane, even with crit. Shouldn't the goal to be to encourage decision making based on actual champion and player skills, rather than just "oh, you're suddenly at a huge disadvantage because they got a lucky crit, what are you going to do now?" Where is the counterplay to crit? Pray harder to RNGesus? Rush a randuin's as an adc? I'm not really seeing how crit chance encourages any sort of meaningful decision making.