Calculate change between two sets of district lines was placed on hold because it contained tags for qgis, R, and arcgis-desktop. The question is said to be "too broad" and "essentially asking multiple questions" simply because it contained the three tags. If you look at the question itself, it is a very concise, specific question about how one might measure a certain geographic property. It does not ask for step-by-step instructions on how to achieve that measure, but rather what that measure might be.
The question itself doesn't mention any software packages at all and describes a candidate measure in terms of basic geometric properties/operations, so an answer in those terms is presumably fine with the questioner, and hence the software tags are somewhat irrelevant. The tour explains that tags are to help find related or similar questions. Thus, I could understand an edit or moderator comment that the tags are incorrect, but not the assertion that by tagging two GIS systems the question becomes two questions.
There are 600+ questions on this SE site with two or more of the cited tags, so it's pretty clear that the practice has been broadly tolerated up to now. Moving forward, are software agnostic questions tagged with multiple GIS software packages to be closed for being multiple questions, edited to remove extraneous tags, or yet some other resolution?