I should add that I completely ignored online communities for D&D, beyond downloading the SRD, and using e-Tools, until after 4E was launched. Relevent fact: I have worked in the web development industry since 2000. I know what a forum is (and indeed how to create one from scratch in multiple programming languages).
I *started* posting on WotC's boards when I was DM-ing 4E. I don't really feel that as a fanbase in the same way as my local clubs and friends I play with and meet.
So my feelings of what a "fanbase" or "community" is seem to be separate from online forums, and that was not due to any ability or opportunity to access them.
Well, with all due respect, I'd have to argue that your feelings of what a fanbase or community is aren't therefore aligned with the reality of the thing. If you simply chose to include geographically local events in your sample, you're only saying "the fanbase right where I am here right now". And, using that metric, I'd respond that, in that case, there is not and never has been a D&D fanbase apart from about 6 years ago when that shop in town opened up briefly for a few months.