Well, okay. I guess it looks like you're right. I heard from someone that a valve adjustment would do some good for blowby, but it might not.

It seems that if the valves were leaking, they would leak either into the exhaust or back into the intake - not into the crankcase. (thanks Ken300D)

And if anything, poorly seating seals would decrease compression, forcing less blowby past the piston rings.