Wow, I guess need to go check Meta here occasionally.
Yes, I added the tag to several posts, as I saw that there were several questions about it and it seemed analogous to the turbotax tag and the like.
For the referenced question in particular, I interpreted the question as confusion over why the form software calculated a value in a particular way. That is, I first read it as a question as much about the use of the software as about the tax form itself.
I agree with the general principle that software-specific tagging should be limited to questions about the use of particular software. This does lead to the problem (not unique to this site) that sometimes one doesn't know whether the issue is related to the software or not until after one has the question answered. That is, many questions can be "Am I using the software wrong (clicking the wrong button for the thing I want), or are my inputs wrong (the software isn't really the issue at all), or is the software buggy (rare but not unheard of)?" And it's hard to know which is the case ahead of time, so one might be inclined to tag it with the software specifically just in case it is a problem with the software itself.
I can see how once the answer is known, it can be helpful to remove tags that are superfluous, particularly if the tag isn't likely to help future people looking for the same issue. And this question was a borderline case, and perhaps it wasn't needed here. But I think that it could have been useful, and a reasonable thing to have done before the answer was known.