Because the content is different, in this case.

I've been a CR member for something like 8 years now. I use Gmail to read a small raft of Google groups, the bikelist.org lists I like, and a few Usenet groups.

The discussion is more restricted, but there are rules and a mission statement that are clearly stated when you sign in. Members are expected to know them and follow them. One of them is civility, and people have been ejected for not being civil, and for other reasons. It's not like this, run by committee in a rather liberal way. The list organizer set it up to mimic having a bunch of vintage bike buddies sitting around his garage and talking cool old bikes. Off-topic discussions are tolerated by the list organizer up to a point, and generally it's not desired to members to take on a vigilantist role in enforcing the rules. I try to leave that to the List Dad, rather than try to help him out.

There's significant overlap with C&V here, and with Retro-Classic on RoadBikeReview.com, so it's hard to say the best expertise is over at CR. However, some really dedicated specialists are there and not elsewhere.

BTW, I can't imagine anyone not being accepted as a member if they "check the box" about understanding and accepting the rules. I think it's much more likely some kind of mess-up in using the bikelist.org control software, either a code problem or a cockpit error.

Norsk, just try it again. There's no vetting process, or check of your politics and credit rating. It's not as snobbish as people make it out. It's just a grass-roots effort, maintained by skilled amateurs within a limited set of resources. BF is FAR more fully-staffed than is CR.