The other is that the 550 foot (clean TOW) take-off roll of the B is longer than the cat stroke,
Thats the worse case scenario, without a ski jump and no WOD. The AV8-B reduced its take off roll by 75% with a ski-jump, it should be even more advantageous with the steeper angle on the QE class.
Edit: Engines explains it far better than I ever could.