Say that a person who had a 2.3L that was "off the road" and didnt have to worry about emissions testing and the like. What would it hurt to blank off the pcv at the intake and install a crankcase breather on the valve cover?
One reason is that the vacuum system will be thrown off, which in turn throws off the computer, fuel injection, and ignition. Unless you are willing to replace or redesign some of these components, just leave the PVC valve in there; it can't hurt.
all the pcv does is suck oil vapors out of the crankcase via the intake. I was going to blank off the port on the intake and add a crankcase breather filter onto the valve cover port. Just like all the old trucks used to have. No oil vapors going back into the fresh air charge to the motor. Surely it would keep the intake cleaner and have to be worth at least 1/100th of a horsepower. :-)