You do realize that p2pool isn't the only pool to distribute blocks directly to miners?
No I didn't realize. But I've only mined in 2 pools ever, and I haven't studied how each pool works
if p2pool finds every block
A virtual impossibility.
I realize that, but even if it is a block every hour or every other block, the overhead is still there. And you yourself brought up that other pools do direct payment, so if you combine all pools that do this, and combined they find every other block, my thought process is still valid.