Is there a reason for this discrepancy?
What should we do?
Unless you want a software that excels (as every 3rd question asks for "the best"). But as that would be a meta-tag then, you're correct it shouldn't be ambiguous.
But then think to say a word: seeing that as tag might make you think twice before recognizing it as MSWord (and not e.g. word-processing in general) – or seeing
access you might be asking "what does the OP want to access?" before recognizing it as microsoft-access. We should also think about keeping tags in "the same style"; so if you now rename this one to
excel, the next question will regard microsoft-word or microsoft-access – and then?
Most other MS tags have the leading
microsoft- (see: microsoft-onenote, microsoft-exchange, microsoft-access), so I'd rather say powerpoint should adjust to that and be renamed to microsoft-powerpoint.