Combating Spam with only GUI Features
For some spammers each account seems to be only used once, but if you just delete the page without blocking the account, you might notice that the same account will re-create the same page.
You can't prevent the creation of accounts (Captcha is innefective at this), but using Extension:SpamBlacklist you can blacklist the URLs using the GUI. So, once that's installed, you'll be able to manage it yourself.
Just examine the spam messages, figure out which URL they are really trying to leave, and blacklist it by inserting it in MediaWiki:Spam-blacklist (check this for an example). Some spammers place a URL to Wikipedia among their content: ignore that one.
The only issue you'll face is that the extension does not provide a way to monitor how many edits (and what edits) it is preventing, so you fly blind.
