Excellent info on why there's a positive crankcase ventilation system, but there appears to be some fundamental misunderstanding of exactly how and when it works. If it worked as described above there would be no valve, just a vacuum line to the crankcase and no breather at all.

A PCV system only works at part throttle and RPM has nothing to do with it, except indirectly through vacuum. The valve closes above a set vacuum level, to prevent the equivalent of a massive vacuum leak. They open when the vacuum level is less than the rated level, but there is still some restriction, to minimize the effective vacuum leak. The reason it doesn't work at full throttle is simply because there's no vacuum at full throttle.

PCV valves look closed when there's no vacuum, but that's just because the end is folded in to prevent the spring and seal from coming out. The sealing surfaces are behind what you can see and close when there's enough vacuum to fully compress the spring.