Following the discussion in the comments, a good compromise would be to have coarser tags for mathematical topics, such as
There is the issue of what to do with the more generic mathematics that is currently used in a large number (currently ~500) of questions. However, given that removing it is a tall (and quite boring) order, we can just leave it, mark it as deprecated, and stop using it. Questions using it can be slowly retagged and so the tag can slowly go away (at some point, when fewer questions use it and we can thus ensure the safety of the operation, it can also be eliminated whatsoever eg merging it with another tag).
In practice, this change would entail removing most of the tags mentioned in the original question, except for
linear-algebra (and possibly other overly specific tags that will appear or I missed here).
Please upvote this answer if you agree, and downvote if you don't (both are equally important). And of course, feel free to add here any comment relevant to the discussion or propose alternative solutions.