If you don't come from a sailing background, how do you get started without taking a class? I couldn't imagine figuring out which boat to buy with no prior knownledge of what is good??
I had read a lot. Then I bought a Hobie 14 and taught myself how to sail it.
I eventually did take classes--have now gotten through ASA 104. They weren't really "necessary," but they did help me to learn a few things about larger boat systems, and the charter companies seem to ask less questions if you show them a certification.
I would also point out that it is not like the people in the OP just bought a boat, tossed their stuff into it, and started out across an ocean (as we have seen some people say they plan to do). They spent quite a few months sailing around the Bahamas--an area where the sailing is fairly easy and the bottom is mostly soft (meaning, a good area to learn). Only THEN did they head out over the horizon.
Seems like they went about it in a reasonably safe and logical fashion. I am also skeptical that these people have been banned from any blogs/forums, unless we are talking specifically about the forums owned and operated by ASA, USS, RYA, or whatever other certifying agency you want to list. Typically these forums are limited to members of the association, so I would say it is less a case of them being "banned" and more a case of them just not being among the membership who are allowed to use the forums.
At least, that's my guess.