Back when it was relevant I was able to clear O12S without much issue, even one handed (literally - I broke my shoulder and ended up changing all my keybinds to play with one hand for a few weeks of our reclears).

But I have to say if I tried it now I would have no idea what I was doing. I bet that a lot of people saying they've cleared did so long ago and are probably really rusty, used to doing things different ways, etc. Basically like they're totally relearning the fight.

It'll get better once we're further into EW with better gear.