I've just again realized that we have a join tag, which corresponds to SQL. It doesn't appear that the questions have anything else in common, either. Do we still need it?
While it is true that most interesting sql queries involve some kind of
JOIN, that is not universally true. (Many
UPDATE queries do not involve
JOIN, for example.) It is debatable whether those uses of the join tag are worth eliminating. I'd say that they are harmless to leave there.