The hell?

Because that's how mediawiki works. You have to delete all revisions starting from the one that added the offending text up to, but not including the one where it was removed, because every revision contains the entire text of the page. Another reason to adopt liquidthreads.

Ah, okay. Then that must follow, then, that there were 11 revisions before it got deleted. Makes sense now. Thanks.

Yes, that's why you should remove a link like that immediately, then discuss whether it is appropriate or not. It can be restored later easily, but deleting it after a bunch of comments have been added results in a large chunk of the history going down the memory hole.

What was it that was deleted?

The deletion comment is obvious enough, I think