If I remember right like halfway through 3.2 a guild found an exploit and killed him but got banned, and then a few weeks later a Taiwanese or Chinese raid killed it legitimately for the first time.
To add to this, people deemed that fight mathematically impossible. It took a ridiculous raid composition and a really creative strategy to down Yogg+0. IIRC it involved stacking the raid with locks because they could face way from Yogg and drain soul/DoT, and using hunter taunts to bounce the unkillable adds around the room without letting them touch the raid.