difference between 5...dxc6 and 5...bxc6?

In trying to get a quick start book for the jaenish schliemann after getting waxed in it on my first attempt at a rousseau gambit, I've come across a move order kink I'm having trouble wrapping me head around. in 2 lines, so far, taking c6 with the queen pawn yields better results where I've always tried to follow the "capture towards the center" rule.

can anyone explain why 5...dxc6 performs better in this position?

I'm guessing that 5...dxc6 controls the queenside better and it helps the light square bishop jump in quicker. otherwise, dxc6 is just FUGLY to me. it violates what I THOUGHT was an "absolute rule". it also seems that taking with b allows for a much more direct attacking ...Ba6 castle stopper/rook attacker that looks more active than aiming the bishop at empty space with zero targets with a side order of indecent exposure by the king

Hello. It is because once you take with the queen's pawn, you open up the diagonal for the bishop and your queen is already developed.

that's what I thought. thanks.

I like rapid development and mobility.

It's just that, because my understanding of POSITION is super weak, I'm trying to understand why it's better to violate the always (as i learned it) capture towards the center. 5...dxc6 violates one of just a few positional concepts I know. the only other ones I know are knights before bishops (not always of course) and if the center is closed, attack the flanks and if it's open, attack in the center. that's about the entirety of my "positional chess book".

any positional knowledge I have is intuitive and not anything i can put into words.

that whole "light square/dark square weakness" thing is not my language. I see "are pawns in my way or open for business?"