As far as I know, AOL is doing something more than you describe.
It is my understanding that they are blocking some email completely. They are blocking dynamic IPs, which would probably include end users on many cable, dsl and dialup networks. They are blocking IPs with no reverse DNS (most likely was the problem for evcforum). I'm not sure what else they block. I think they do block sites with a record of high spam rates.
You are right, however, that they have a system where aol users can flag a message as spam. As far as I know, if the proportion of spam to non-spam is too high, AOL will block mail from that site.
At my campus, we have requested that AOL send us copies of all mail recieved from campus IP addresses and reported as spam by AOL users. We mainly use this to spot spammers quickly and shut them down. Over the last year we have probably blocked around 5 or so spammers (virus-infected user machines remotely controlled by spammers).
Currently, I get to see these AOL reports. Yes, aol users are careless on what they report. A lot of legitimate mail is reported as spam. However, most of what I see is a student has forwarded his campus mailbox to aol, because he prefers to read mail on aol. Spam is received for his campus mailbox, forwarded to aol, then the user flags it as spam.