It is not really a proposal, and it was not invented by me. Over the years I have seen a variety of CVP editors reject submissions for not being sufficiently different from what we already had on the site, with the remark that they could add the slight rule variation as a Note to the existing article. Usually this happened when the existing article was by another user, and the author that submitted the nearly identical variant was not aware of it. Authors that have nearly identical variants to submit will of course be aware of that, and usually have the good sense to submit them as a single article. E.g. Great Shatranj (with either Rook or War Machine) from 2006, Rose Chess (with pieces either on 1st or 2n rank, 2007), Ajax Chess (10x10 and 10x8 version, 2009). In the Wa Shogi article I made in 2015 I mention both the variant with and wihout drops, even though as far as playing experience goes the feel of these games could hardly be more different. But it only takes a single sentence to mention whether captured pieces can be dropped or not, and IMO it would not make sense to have two separate articles only differing in that single sentence.

There were three recent submissions that only differed in whether in addition to normal FIDE play you could swap pieces only with other pieces on the board, with pieces that had been captured, or with both. My recommendation was that these had better be combined into a single article, and indeed the author has now done so (under the name Swaps, where first there was Inner Swaps, Outer Swaps and Any Swaps). As far as I am concerned that does remove any objection to publication.

BTW, originality is of course not the only criterion for getting published. Playability and quality of the presentation (clarity and graphics) are other criteria that are heavily weighted. And for articles about variants that are not own inventions the originality aspect could be replaced by the notion of importance, e.g. was it described in an authoritive book, is or was it widely played, etc.

You mention 5 variants as examples of being unoriginal, but you fail to mention why (i.e. what variant they are so similar to, and whether that was by the same author or not.) Apart from nr. 5 (the umptieth variant with BN, RN and QN compounds, but many of these being historic) I would not know anything close to the others. Of course 1 and 2 are unplayable, due to the huge strength imbalance (1) and the 'guaranteed-draw problem' (2). Although in case of WW-II one could argue that it would still be a feasible game for players that are close enough in strength that both aspire to win; it doesn't seem easy to build a fortress once the pieces are spread over the board and it becomes clear that your opponent is getting the upper hand. If it had been up to me I would have certainly rejected 1. (Even the graphics suck there!)

A case that I encountered is ZigZag Madness, which in the Notes mentions to be closely related to two other variants by the same author. The unorthodox pieces in two of these three variants only differ in that one is the sliding version of the other, in the sense that a Ski-Bishop is the sliding version of an Alfil. In defense one could say that the largest part of these articles is devoted to elaborately explaining how exactly the pieces move, and they are different pieces needing a different description. So not much of the text is duplicated. This makes it quite different from the case where two versions of the same exotic piece were used instead of one of each.

And now that we are at it, can you explain why you have time for distracting me from my work of equiping hundreds of articles with Interactive Diagrams, many of these yours, by typing Comments that are even tedious to read, instead of saving me some work by equiping your articles with such Diagrams yourself? I would think that this site would benefit far more if you started to do something useful for a change, as you apparently have time to waste...