Lopen is vastly downplaying the difficulty in Inferno. Act 1 hasn't been nerfed and was decently challenging when first arriving there. It wasn't one shot hell like the later acts, but you could certainly die to a lot of stuff, especially to difficult combos.
It's easy to forget it being difficult when after you've farmed even a decent amount of gear (200-300 all resist with 30k+ hp) that the stuff there will now tickle you. But typically when you get to Inferno you have no all resist and more like 20k hp. I remember the first time we got to the skeleton king and everybody in my party kept getting one shot by his blink strike.
Such a thing is laughable now but yeah, when you have no gear you really do die. I remember the Butcher's cone chain attack taking over half my health every time it hit me when I first got to him which was not nice.
Act 2 won't one shot you any more, but it still does decent damage even if you have a chunk of resists. Not getting one shot =/= super easy. Getting one shot by everything when you had 300-400 resists in act 2 was ****ing stupid.
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The batman villians all seem to be one big joke that batman refuses to laugh at - SantaRPG