While reading "Does this armor set work RAW?" I stumbled upon the powergaming tag for the first time. Because I felt the overlap with optimization should be quite large, I proceeded to have a look at the only 19 questions under this tag.
I think they can be sufficiently categorized into three types (number of questions per category in brackets):
optimization questions. Some already have this tag as well, others (like these four questions) can be reassigned (15/19).
problem-players, such as these two, or this one that already has this tag as well (3/19).
No additional tags needed at all, such as the question I quoted above, which would work just fine with pathfinder armor rules-as-written (1/19).
I therefore think the tag is highly unnecessary and should be purged in the flames of hell removed or reassigned.