Eh, people stacking corruptions is just burst damage. Sure, lucky procs can instantly kill someone but usually if you play smart you won't die from it. Balance is what happens throughout the whole season, not what happens in a single game where someone had lucky procs.
The problem with destro is not his burst. It's not his CC. It's not his survivability. It's all of it together. A destro just goes into an open field place as far away from pillars as he can and completely controls the match.
Destro skills have some insane synergies with each other