I've always viewed it as related more to internal vacuum, and a combination of factors not limited only to the PCV valve.
Yes, the main idea behind the PCV valve is based on reducing emissions (burning off oil vapors rather than venting them to the atmosphere), and if that were all that were coming into play where a VX was concerned, then keeping it in place would be best for the VX and the environment. Plus, if oil vapor leads to sludge, venting it would seem to address that problem.
Unfortunately, poorly considered piston and ring design are also factors in this case. Over time, a lack of drain-back holes in the piston bodies leads to accumulation of oil-based sludge on some piston rings, which in turn leads to the piston rings creating even MORE vacuum than originally intended for on the intake strokes, which in turn leads to even more oil vapors being drawn into the cylinders via the intake and PCV systems. In short, a vicious cycle.
Maybe it's simply a question of catching it before the cycle ever get's started that accounts for whether a person has oil usage even if using a breather filter instead of the stock PCV system, maybe not, but I'd personally rather not risk it. Can current piston/piston-ring build-up be eliminated (Seafoam, etc)? Probably no way to really tell short of engine disassembly, but some here seem to have had some success trying that too.