I noticed the same problem, but I admit that the first time I posted something on perlmonks I created some empty nodes too: I never understood how that happened. Anyway I'm almost sure there is a way to recognize empty nodes, so why not writing a nice perl script which may run daily and delete all these useless nodes? In this way everybody is still allowed to post, but if someone post empty nodes - either for mistake or on purpose :( - these are soon removed.
marcos