I don't think they are actually editing the page, the message is just the page being automatically created when the account is registered.

I believe there was a measure enacted recently that put an extra step (email confirmation) between registration and the ability to modify pages. This was because there was significant amounts of actual spam (not just spam accounts) being posted, which seems to have been entirely stopped.

(ETA: and also requiring a captcha when inserting external links into a page, at least for new-ish users.)