Thread:Project:Support desk/Spambot users with no edits

This is my wiki

I have MediaWiki 1.16.0, PHP 5.3.6 (cgi-fcgi), MySQL 5.5.17

I have spambots logging in and creating accounts but I have set up the wiki so that they do not make any edits. Is there any harm in having many spambot users if they cannot actually add any spam? Also is there any way of stopping new account creations from appearing in recent changes?