Every time we build on this system we run into all kinds of inconsistencies in data. And contrary to what one might thing, we don't seem to be filling in the missing pieces, so it's not like they serve as a convenient shortcut.
Recent changes are a temporary snapshot of revision and logging. So it makes sense that, as long as it supports recentchanges, it must also support both revision and logging. But do we actually tag log events? Specifically log events that don't have a null revision associated with them.
And do we ever use change tags directly on rc_id exclusively? Because recentchanges already has rc_logid and rc_this_oldid readily available. Seems like there isn't much use in associating a change tag exclusively with rc_id. Especially considering recentchanges continuously rolls over and the tags would be inaccessible (but remain in the database?).