Actually, my impression is that the TM tend to be differently tolerant. For example, “the Dope” tolerates “homosexuality” in that no one is going to be castigated for being gay, bi-, or straight. However, it is not tolerant of the issue of homosexuality. Any poster who questions any political or societal decision that might be remotely construed as hostile to supporting absolute rights for homosexual will meet a firestorm of criticism, and often abuse. We have seen decent posters wander away from the SDMB because a fairly mild comment reflecting older attitudes has resulted in them being hounded on the issue until the SDMB stopped being worth the effort. We are not there, yet, but there is a certain trend in the same direction regarding religious beliefs. We have lots of endless and never-resolved debates as to whether there is or could be a god, but particular discussion of aspects of faith have been driven off the board as (for example) anyone who wishes to discuss Premillennialism, Dispensationalism, Amillennialism, Preterism or even a comparison of eschatologies between faiths more widely diverse such as Christianity and Islam or Judaism or Hinduism will find that their conversation has been driven off by the folks who have a desperate need to wave IPUs and FSMs at them.
On the other hand, essel’s point regarding the number of people who can control a discussion is also true. I have no idea how many people really wish to drive away anyone who does not view homosexual activity as an absolute right, but I can guarantee that those who champion that view are more than willing to be pretty strident in their attacks on opposing views. Similarly, even with a disproportionately large percentage of atheist posters (when compared to the general population), I find that the majority are willing to take a live-and-let-live attitude toward those crazy people who believe in the spiritual, often even being willing to participate in discussion in a way that is not intended to silence it, but there are enough of the more strident posters that threads on such topics, (and, more importantly, posters who are interested in them), do not survive long.
Beyond that, of course, a lot of people who are nearly libertine regarding some issues, “balance” that in their lives with a rather puritanical view of the world in other areas. We’ve got lots of posters with a(n un)healthy streak of judgmentalism running through their world views. They will fight to the death for someone’s right to break taboo A while heating up the tar, plucking the chickens, and looking for the most splintered fence rail to use on any poster who might offend taboo B.