There was a boss in Vanilla WoW that was mathematically impossible to beat. I'm sorry, but Vanilla Naxx and the last 2 bosses of AQ 40 were very difficult.
Just ignore people like him. If he seriously think that they are going to have truly difficult nightmare mode bosses with enrage timers, and not add in a combat log, then he's crazy.
There's nothing EZ mode about not wanting to get to a point where you can't mathematically respec anymore. Hell, make respecs expensive, I don't care. But at least cap them at a point so they're still available.