Later two new tags least-common-multiple and greatest-common-divisor were created. Already the creation of the new tags, despite the fact that gcd already existed, may suggest that some users were not satisfied with the fact that gcd was made a synonym of divisibility. At least some users voiced this opinion in comments. Both these tags are suggested synonyms for divisibility. I recall seeing some downvotes there. (IIRC when I first saw that page, the total score was -1, meaning that there was at least one downvote.)
I think that the tags gcd, least-common-multiple and greatest-common-divisor should be dealt with in the same way. Having several tags for the same thing seems rather messy. The problem with these tags was also pointed out recently in chat.
So it seems that we have two possibilities:
- Make gcd again a tag separate from divisibility, i.e., cancel the synonym. (I am not sure, what happens with the questions currently tagged as gcd in this case.)
- Make the other two tags synonyms of divisibility, too.
I suggest that until some kind of consensus is reached, we should use both greatest-common-divisor and divisibility questions about g.c.d. This will make things easier if we later want to separate the tags - less posts will be needing retagging.