Isn't there a disincentive built into MO by automatically making a question with 8 edits become CW? After that the user can still bump the question with minor self edits (at the expense of others), but won't get any reputation for it. On the other hand, Ali's question you linked to appears to still not be CW, so perhaps this was only for an old version of MO. I found a reference that reminded me why I thought sufficiently many edits made a question CW:
http://mathoverflow.tqft.net/discussion/170/too-much-editing-turns-questions-into-cw/

http://mathoverflow.tqft.net/discussion/69/the-sixedit-limit-is-nonsense/