I'm a former iOS EPM (not speaking for Apple, obviously, since I don't work there anymore), and although the Reddit commenter got the atmosphere of constant crisis right, he/she is misplacing the blame and misunderstanding the power dynamic. EPMs at Apple essentially have zero power over engineers' workload. They take the list of stuff the engineering managers said they want to get done this year and say "You guys are crazy, you'll never be able to do this without 3x the hours/manpower." Then they proceed to drive the team as hard as necessary to make sure that they actually deliver what they said they were going to deliver. That's it. The idea that there is this cabal of mighty EPMs twirling their mustaches and loading developers down with work is pretty far from reality.
It's true that you shouldn't be working on anything not in Radar (the bug tracker) but this is true anywhere you'll work. Project managers however do not sign developers up for all those radars--on the contrary--we're usually trying desperately to help you get rid of scope and get the task list down to what's actually do-able!
One of the great things that IMHO sets Apple apart is how engineering-driven they are. I've never worked anywhere else where engineers had so much freedom to decide what they're working on. The fact that they always decide to work on 3x what they can actually achieve is kind of on them. But that drive to try to do so much is part of what keeps innovation strong at Apple.