Is there an official position on this? Do we or don't we like adding "belongs-on-x" tags when closing? Personally I don't like it at all, since it's editing the question itself to support the closer's opinion, which hasn't been validated by the community yet.
I agree with you. I don't see what purpose the tags serve. Is anyone going to search for posts based on a "belongs-on-x" tag? I don't see why they would. They just cause a little more work when a post does get migrated and the now silly looking tag needs to be removed. I remove them when I see them.
For the record, the official position from Jeff is that belongs-on-* should not even exist:
I swear I thought there was also another answer of Jeff's on this question ... But I do not see it anymore.
That's about as close to official policy as we can get. I started retagging a bunch of
[belongs-on-superuser]-tagged items last week when I started seeing it a lot on SO. (Mostly guys who just got the ability to retag.)