I personally think there's different flavors of randomness. There's fun randomness, and there's frustrating randomness. Crits feel like you gained something through randomness, and random loot can be exciting. A range of damage is kind of inbetween, not very interesting, but sort of feels a little realistic I suppose. Randomly getting your CC resisted or getting a bad roll on resisting it yourself just feels lame. Sure, it's a factor for balancing, but not a very fun one for most people. Missing isn't much fun either, but the stakes usually aren't nearly as high (a single hit vs. a crucial CC with a long cooldown for example).
RPGs don't require randomness. In fact, I could see an entirely non-random D:OS2 without losing all that much. All attacks hit, no crits, no misses, no damage range, all placed loot. While it would require some rebalancing, it wouldn't be that much. You say RNG represents character abilities to simulate their skills based on their statistics. That's just one way to represent character skill; decision making, represented by the player, is another, ultimately much larger factor. Basically, an RPG Tactics game, which is mostly how the game is designed already. You can still roleplay and develop characters and have skillful combat without a drop of randomness.
Now, slight randomness can help make the game feel a bit more organic, which is fine. I personally wouldn't want to see zero RNG whatsoever, but it would hardly kill the game to do so. The armor system needs some work for sure, but I don't think Larian is throwing it away. I'm still a fan of minor and major statuses for armored/no armor opponents respectively.
I think you're right though that hard CC is pretty much a no-go with an RNG system. Less dramatic statuses could absorb some more randomness.
