SECTION 3: PARACHUTE
252 SpA Life Orb Mewtwo-Mega-Y Fleur Cannon vs. 252 HP / 252 SpD Mewtwo-Mega-X: 395-465 (94.9 - 111.7%) -- 68.8% chance to OHKOCurrent meta, Xtwo is guaranteed to survive and retaliate as long as it doesn't switch into the attack.
same applies for giratina, all non regenvest variants get 2hkod even without life orb. trying to set up on full hp giratina is a bad idea regardless but i digress.
anyway considering your main argument, i disagree with the idea that contrary isn't broken now because it wasn't broken in the past.
even if we went and banned sunsteel/moongeist/photon, there are still things like dazzling preventing you from running topsy turvy (balance's counterplay to contrary in gen 6), unaware cress still being bad because of power trip, everyone running mold breaker pursuit for shed (it's already a thing if that's any indication) and more. it doesn't fix the problem.
mold breaker moves aren't the problematic element. the problem is contrary preventing prankster haze and being almost impossible to reliably take on defensively. btw if you use v create mmy can you actually quit mons please thanks -pheromosatl