Part of the discontent with this is, I think, the seperation of skill level. Competition play doesn't include critical hits because the fanbase's meta believe that the mechanic doesn't accurately reflect the player's skill. In public gameplay, there's other stuff going on- different skill levels mean that the field of play can be leveled a little bit by intervention. Another important point to consider is that the scaling damage mechanic increases survivability of the weaker classes. A sniper can deal a massive amount of damage at range, only for a spy or a pyro- someone with a class advantage in close quarters- to close into melee range. The sniper's performance - i.e. skill - will allow them to fight that threat. Same goes for Engineers or Medics- if someone closes with you, you're screwed, right? An engie's sentry gun cranks out a ton of damage, which counts for crit chance. Medics go by assist damage, which counts for crit chance. If you've been doing well as a support class, you might not be out of luck- luck actually bends for your favor. The scaling damage of the crit mechanic encourages people to play support.