Some admins of private servers blocked its IPs for the same reason IRC mods did. AOL got ordinary people on to the internet, so they were a poorer fit for any existing community on average.
Once upon a time, cs.utexas.edu ran a well-known email-to-news (i.e. NNTP, Usenet) gateway. After some problems, AOL's admins asked the person who ran it to block AOL email addresses. Yeah, this was years ago.
Some time later, a person who had an AOL email account (who some of you might recognize, so I won't name names even though I'm dying to) contacted the sysadmins, complaining that the email-to-news gateway wasn't working. When she learned that AOL addresses were blocked, she threw a tantrum, threatened to contact various newspapers, complained about UT blocking public access to things paid for by public money, and so on. As a result, the mail-to-news gateway was shut down.
https://en.wikipedia.org/wiki/Eternal_September
Some admins of private servers blocked its IPs for the same reason IRC mods did. AOL got ordinary people on to the internet, so they were a poorer fit for any existing community on average.