The tag maxima-minima should not be a synonym of optimization, neither should be the tag max-min.
Given the historical tag description of max-min I'd agree that it was reasonable to propose it then, but I still think it is not a good idea.
The reason for my view is that those notions, maximum and minimum, also arise sometimes in contexts that have nothing to do with optimization, and often arises in contexts where the link to optimization is tangential.
For the former I think of usage with respect to order relations in general. Abstractly, one could also make a case that a tag for maximum and minimum should be a synonym of order-theory. (It should not be, either, but it would be just as valid as optimization, in my opinion.)
For the latter I mean all the calculus questions that ask for local maxima and minima of some function maybe together with poles and asymptotes. That's not really about optimization. I think having all those under optimization somewhat pollutes the tag, which should be dedicated to questions that are actually about optimization.
Or, questions about whether some set of real number has a maximum, that's not optimization. (Right, one could construe it as a question about extrema of the identity function, but that's contrived.)
Thus, my proposal is to keep the tag maxima-minima separate and to make max-min a synonym of that tag (or to remove it entirely).
I'd do the same with extrema but that's a bit less important.
Generally, I think we should avoid all synonyms where there is a risk that questions get a tag that is just wrong for the question. Ambiguous tags should either be accepted or they should be avoided, but they should not be synonyms of one of several use-cases, even if that is the most common one.