For many reason, the entire raid is much more difficult at the actual light it was intended for. The raid difficulty gets ridiculously more difficult with even 1 person down(very punishing). So it meant you couldn't bring/backpack some of your lesser skilled friends through it because they would die and you would wipe. The mechanics were pretty good, but again relied on almost the entire team to know all of the jobs so you could switch on the fly(back for pug's). VOG just needed 1 good relic holder and you could carry just about anyone through, Crota you just needed a sword bearer, a warlock and a damn tracking rocket. So very few people actually completed...it was around 5% of the entire destiny population had actually beaten hard mode before the light increase. I completed about 100 times at 320 light, but it was a struggle with pug's everytime. It took a lot of groups 3-5 hours to complete, a good run for my team was about 40-45 minutes, but the wipes for uncoordinated or pug was very time intensive