This is related to the question about top-level tags.
It seem to me that the tag computability acts differently than other tags. While it belongs to the top-level tag lo.logic (is it?), a large number of question with computability just don't have any top-level tags. I guess some of the poster raises their questions in the field out of lo.logic, and it is just hard to think of this top-level tag while posting. And maybe some of them just think that computability is the top-level tag.