I've always wondered the same thing. I've tried everything out there, with the SweatHawg skull cap being the only thing to end up working well. Regardless, it just delays the inevitable. And while I'm out searching for new ideas to try to keep the sweat out, my riding buddies ride along peacefully. Anyway, the point is, I'm right there with you!
I noticed it more when mountain bike racing, so the position argument could hold some weight there. But I also spent more hours racing off-road, so naturally I'd deal with more sweat there.
I just try to deal with it!