Then you should know better.
Your argument makes no sense:
Dota 2 has a multi-million pound tournament on at the moment, its unarguably "competitive" yet it has plenty of RNG:
- uphill attacks 50% chance miss
- evasion, bash, crit strike, maim - all random
- countless proc abilities
- auto attack min/max
It also has plenty of players fighting the environment in the creeps. The neutral creeps have min/max damage and will randomly target enemies with abilities when criteria are met (3 units within aoe of their spawn).
All of these are obviously in the game on purpose and I could make the same arguments with practically any sport or competitive game with the possible exception of chess (it is described as the "pure strategy" game after all)
You mention lol as your example of a good strategy game, again it has countless random components.
I agree that there are aspects of Coh that go way overboard with randomness.. plane crashes springs to mind, but your assertions that reducing randomness always makes things more competitive or is good "game design" is objectively wrong.