I agree with you in some respects. Frankly, any documentation is more than we get with a lot of our 9mms, including ones sold at St. Louis for a lot of money. Still, I buy them when I can, and hope they don’t turn out to be fakes. People ask me why I am more interested in a common round with a new headstamp that I am in the rarest prototype there is in some headstamp that already exists. Simple - with a very few exceptions of faked headstamps, not common in the auto pistol field, (am not counting Asian headstamp rip-offs as “fakes” here. They were manufactured to deceive the buyers who wanted to shoot the rounds, not collectors, and have a “story” of their own that makes them collectable). a headstamp is a headstamp. It is not some common case with the wrong bullet shoved in it, or some exotic shaped bullet that an amateur machinist could turn out on a lathe in a half a minute. Much safer. Still, as I said, I buy the exotic bullets and hope they prove to be real.
Your analogy about the WTP and WP headstmaps is strained for more than one reason, one of which I will mention here. Again, regardless if we had no idea who Winchester made it for, we would buy it, because we found WTP 95 on the US Commercial (mostly gunshow) market in boxes, and it is a headstamp few of us had before then. A headstamp is a headstamp is a headstamp.
Again, though, I agree with what you said. We all have rounds, me included, that we have no documentation for, some no more credible than those “dummy” rounds. I just have limits of interest as to what I keep. It is for everyone to decide what they want. I don’t collect dates in my auto pistol collection, but I collect every date in Makarov cartridges, simply because I like them and collect the pistols and everything else that has to do with them.