At the risk of seeming a bit quick off the blocks, I think I've gotta close this thread. It rests on fundamentally incorrect assumptions about this wiki. As such, it's too flawed to allow to stand. Here are a few reasons why:
- "...We always seem to be bringing up the same few stories declared “non-canon” on the site long-ago." Well, no, "we" don't. And neither is it right to say that "we are still fighting over" whether Peter Cushing films are valid". There are a few people who like to bring it up from time to time, often in violation of T:POINT. And as we learned in the spate of inclusion debates in December 2016, some participants were actually opining about things they hadn't ever read, seen or heard. They were just jumping on the bandwagon. So I'm not at all inclined to believe that this is some big, pressing problem. I'm always going to be on the side of the average reader of the site — and none of this is even on their radar. I know from page view stats on the wiki that, over time, what most people care about are, unsurprisingly, characters from modern (mostly televised) Doctor Who.
- "Because it's been routinely agreed upon through precedent that our rules have evolved to create a difference between a story being “non-canon” (of a different universe) and “Not-valid” (not suitable to be covered on this wiki as a feasible Doctor Who narrative) ... " That's simply not true. The rules do not create this difference that you suggest. The only things this wiki cares about are valid/not valid. Yes, this wiki is old enough that it predates Paul Cornell's famous and fan-influential "there is no canon" essay. So you'll find some earlier discussion material that uses the word "canon", where today we would use "invalid". But for the better part of a decade we have been saying the same thing. You can see this in the very first iteration of {{Invalid}}, where the language says exactly what we actually say today about {{invalid}} articles: "Do not reference it in an article written from the in-universe perspective". So if you see an admin using the word "canon" in the last decade or at the top of this one, what they generally meant was "this thing can be used to write an in-universe article" — exactly the same meaning admin assign to "valid/not-valid" today.
- We have not been using "canon" as has been suggested by the OP. The whole point of T:CAN is that we don't care about canon here. Tardis admin are not trying to define that term except to say that it does not exist in this franchise.
- The whole of #Defining Words and #A History Lesson, above, is therefore built upon a fundamental misunderstanding of the wiki's history and ambitions.
- "These days we consider non-valid stories to be ones which we are incapable of covering." Again, no. That's not what "non-valid" means. A non-valid story is one that can't be used to create the in-universe portion of an article. It's right there in the opening couple of paragraphs of T:VS. In fact, the OP's defiinition is almost precisely the opposite of what the term means. It's not that we can't cover something deemed {{invalid}} — we have long allowed coverage on Dr. Who and the Daleks. It's that Dr. Who and the Daleks is not a valid source for the in-universe portion of the page Dalek.
Understand that by closing this thread, I'm saying quite specifically that the logical underpinnings of the original post are just too shaky to allow for further discussion. I'm not saying we can't look for some kind of reform. Indeed, I've been thirsty for some simple thing that can be easily administered and understood. It was always the intention in the creation of this discussion board that it would eventually no longer be needed.
But I really think that by firmly pushing back against the OP's assumptions, it might put us on the same page — and help frame future arguments along clearer lines.