RNG is fine as long as it isnt rare AND extremely impactful AND unmitigatable.
Yes! A 1000% this. This is the problem with mechanics like Abandon and Main Gun Crit.
It's also really obnoxious when a tank instagibs an entire squad because they clumped when the tank shell hit. There's certainly a weird consistency problem, where King Tigers and IS-2's are unable to one-shot squads but ordinary stuff like Panzer IV's and T-34's are still perfectly capable of it. The range of RNG variance on an ordinary Medium Tank shot shouldn't vary from miss to instagib entire full squad. I think the maximum models hit per squad modifier (like on the T-70 now and mines) should be used across the board for most tanks. Being punished for not doing anything wrong is so frustrating. Infantry clump up all the time when moving around, you can't always avoid being clumped when moving and risk getting instagibbed.