Is there any benefit at all to a rooks' pawn opening? Many beginners open the game with moving their a or h pawns. 
Is there any benefit at all with this opening?
Apart from the fact that you can develop your rooks (which isn't good so early in the opening, because your rooks might become vulnerable), the only other "benefit" I can think of is that a4 (more likely than h4) can be useful after some transposition to a normal opening, e.g. stopping black from playing b5.

That being said, black can comfortably choose (thanks to your gift of a tempo) an opening where a4 is useless.

The other move 1. h4 is even more problematic because castling kingside is much more frequent than castling queenside and h4 weakens the pawn shield in front of your king.



So I don't think it's worth calling these possibilities benefits at all.