It's not exactly about the original question, but now proofs has been duly removed. There are still the tags alternative-proof and slick-proof (47 and 17 questions respectively at this date 2020/Feb/06). While in practice they have close meanings, the second one is unpleasantly non-neutral, and I...
@YCor I will just point out that it's possible that if that was a new question, it would be slightly more likely that it gets noticed.
Questions which are tagged discussion and have score 3 or higher and are at most 14 days old are displayed in the community bulletin. (This is answer to an old question, so it will not be shown there.)
My personal impression is that posts which are displayed in the community bulletin usually get more views.
OTOH I understand that this is related to the topic of the older question and you might consider preferable not to have too many questions about the same topic (or very close topics).
> While in practice they have close meanings, the second one is unpleasantly non-neutral, and I'd like it to be removed, practically making it a synonym of alternative-proof would sound fine.
Is it more-or-less in the spirit of your suggestion on meta?
I am asking partly because the question was recently bumped - so it is a good time for retagging or other improvements without causing objections by MO users. And partly to check whether I understood your proposal on meta correctly.
Let's hope that your post on meta gest some feedback from MO users. (Quite often tag-related discussions on Meta MathOverflow got with no - or very little - response.)
I've finished to retag the (about questions previously tagged semigroups-and-monoids (which were previously tagged semigroups before creation of the latter tag), which pertain to this subject. There are now 391 questions tagged semigroups-and-monoids and 82 tagged semigroups-of-operators. The split was almost obvious to do, because it corresponds to questions by essentially disjoint community. I put both tags only at one (somewhat open-ended) question.
Most questions in semigroups-of-operators have among its main tags, ap.analysis-of-pdes, fa.functional-analysis, pr.probability. Many share the tag operator-theory. In most cases these other tags were already there, but I did some little tag changes.
There are a few questions with fa.functional-analysis which I left in semigroups-and-monoid and didn't tag semigroups-of-operators, e.g., about harmonic analysis on semigroups. It is quite distinct from the somewhat homogenous style of the use of "semigroup" in questions currently in semigroups-of-operators (which is always 1-parameter, where in some exceptional ones the parameter is complex).