I have been on the internet way before the www existed. Back in the beginnings of Usenet only civilized people were around. Because computers and internet/arpanet access were rare, expensive, slow and only scientists and people knowing how to do more than push an "ON" button communicated with you. This changed rapidly. Now every freak, murderer, rapist and mentally challenged person has internet access.
Google and other search engines (like Wayback, Whois etc.) make it really easy to connect all the information about a person. I might have expressed my political, religious and other views somewhere to some minor degree - although I don't take part in stuff like NPR. I do not want some freaked out extremists of any kind to be able to easily profile me. Including home address, phone number, my lady's address and all that. That is why I don't use the same screen name in other forums, either.
OTOH, if someone wants to contact me and I don't feel he is a nut job they can have my name and all. I met several people in RL that I only knew from the net. But again - no need to post my full identity all over the place.
I also had idiots follow me - not in RL (thanks heaven) yet, but on the net. One major a** followed me to 2 other totally unrelated forums back in the day when I used the same screen name on several. Only because he was some freaked-out nazi I had a minor political difference with in some thread. He tried to jump on me in forums he personally did not have the least interest in.
So, there are good reasons for a bit of anonymity.
WRT to AZB: I never pretend to be a better player than I am. Actually, I tend to be more modest in my self-perception than quite a few people I have later met in RL. Not AZB people, but from another international pool forum.
One funny story that happened in another forum was that I discussed a combination shot SVB made in - I think it was - the Mosconi Cup. Which - IMHO - was at least medium hard for a pro. Several people jumped in and berated me how easy that combo was. And that they would make that something like 8/10. One guy was extremely outrageous and said he'd make that shot most of the time on his table with 3 3/4" pockets. Jeez. So I searched the guy's posts in that forum. Guess what?
He posted a few months earlier that he got himself this wonderful 5' table. (He could not even have set up the SVB shot on such a table because the total shot length was over 6'.) *bg*
People bragging like that are all over the internet. But then again I don't see a reason to believe anything posted in some forum without knowing the person. I always double check stuff unless, for example, a known "great" like Tom Wirth posts something about 1P. Also, after reading a forum for more than a couple of months you start to get a feel for people - anonymous or not. And there are more than enough d*bags posting under their real names as well. Sure enough, it is easier to post bs anonymous but a real name is no guarantee for a nice person.
Then, even someone who is not a great pool-player might still have a lot of useful information for others. Examples would be people who don't always buy the latest craze and if they do, they judge them honestly. I remember a time when I read that Kamui chalk was "simply the best" from a lot of better players. Some beginners already said that it's dirty as hell. Just as an example.
So in the end I don't believe you have to be a pro-level player nor present a "real name" in order to be a valuable asset to a forum. Stupid people can be recognized after a few dozen posts, normally. And some of those are really good players.