I mean, really it comes down to statistical balance vs numerical balance.
It's the difference between an ability hitting for 50 damage 100% of the time and it hitting for 100 damage 50% of the time.
Statistical balance is very binary, in that you don't get chip damage or any of the secondary effects if you miss a skillshot or, more specifically, they dodge an ability with their mobility. Compared to a kind of continuum style of balance, which most secondary effects are reliable, but the primary effect might get heavily mitigated.
Now take this logic to the extreme, what would people prefer to play? A 1% chance of dealing 100% maximum enemy effective health (through shields) as true damage or an 80% chance of dealing 1.25% of their maximum health as true damage? Where you really start to see the issues arise is in the surrounding aspects of the game, though my words are failing me at trying to properly articulate my thoughts. But just play out in your head how each of those designs would play out when you start to consider how you'd handle resources, respawn timers, objectives, exc.
^ what's really scary about that is how accurately it predicts many of the problems we see in the game today... js
