Every new requirement is extra work, the question is always whether the extra work is worth the effort. I think here it is.
First, setting up a group is optional and not required.
Second, having one (or more) tags for a collection is generally helpful even if nobody (or no maintainer) subscribes to these: they allow to search for other discussions on the collection / its contents without having to rely on using the right keywords in the free-text search. This is quite an improvement for Ansible users IMO, and thus worth some (basically one-time) extra work for collection maintainers.
community.general and community.network are special in that most discussions on the forum for content in them, using the tag doesn’t make sense. It mainly makes sense when talking about the actual collection, or asking questions on the collection structure, the content for it, etc. IMO having a specific tag for these collections does make sense, but it should be used differently than for other collections.
(And there are situations when having a group for it at least temporarily could make sense as well. I didn’t request groups for any of “my” collections so far, only tags: Requesting a tag/forum group - #34 by felixfontein)