I don't agree with the "it's better than nothing" statement. We already tell people to "go read the tag wiki." So now they go read the tag wiki and it's only a link. Basically saying "ok, now go read this website."
A link-only tag wiki is just as bad as a link-only answer. It's not useful. We want the information here. I'd have no problem with adding a link to the official site if it wasn't there before, but only adding a link to an empty wiki just doesn't help anyone IMO. The key point here is that edit creates a bad tag wiki whereas adding a link to an existing one is improving an already good tag wiki.