Why is the oil pan so hard?

It looks like cavemanmoran pulled his engine with the hood on. I always thought the hood had to come off, which is a hassle since it never seems to go back right and I never have a helper.

I've always left the hood on when I've pulled early A engines (both V8 AND slants. Gotta raise the car, angle the engine and be careful. Done it both with a helper (my wife) and by myself - that's definitely a PITA.