Your Turn to Teach Me Something

This is not a statement, and this is not a rant. This is an honest-to-God question. I'm hoping to start some discussion here, or at least, having some people enlighten me. Really, I'm trying to understand.

Some backdrop: I was having a discussion with some local veteran community members the other day. One of them, a Dom and Sadist, happened to make a comment about the "kinds" of subs he likes to Top. I'm paraphrasing here, but basically the conversation went something like this:
Him: I would never play with a sub who tells me she has no limits.
Me: Why not?
Him: Because every sub has limits. If she doesn't know what hers are yet, that's fine, but I don't want to find out the hard way. If she's so new she can't even give me one limit, then I step back and say 'sweetie, come back to me when you discover a limit or two, and then we'll play.'
Me: But what if she really has no limit? What if she'd let you do anything you want?
Him: Then she's mentally unstable, and I don't want to play with her anyway. I don't play with crazy.

At this point, a lot (I won't say everyone, but a lot) of the people in the room started nodding their heads, like, yes, he's right, a sub with no limits is crazy.

So there seems to be this prevalent notion that subs, if they have any self-respect at all, if they're mentally sane, have to have some limits. Because not everything should go; a Top should not be allowed to do whatever he wants. That's foolish and dangerous. That could lead to disaster.

So here's my question: How come this rule doesn't apply to the kink community as a whole?

We're fed this belief that in our community of Sadists and masochists, debauchers and hedonists, everything goes. We repeat the mantra 'your kink is not my kink, and that is okay.' We're expected to erase judgement from our minds, treat it like a dirty little crime, never talk about it except with an air of disgust, a tone of contempt.
(As if we all could erase it from our minds. People judge other people. That's what we do. We can try to curb it, keep it down to a minimum, but we can never "evolve" ourselves past it.)
But if we have a community that accepts everything, and deplores nothing, refuses to entertain the idea that some things should just not be abided...
Don't we end up with a community full of crazies?

I really want to know why people seem to have this belief "a community without limits is a good kinky community." How is it good? How does it help the strength and growth of the community? I understand you want to protect it from the kind of discrimination and prejudice you find in the vanilla world. But surely, going to the opposite extreme of Anything Goes can't be healthy, either.
Can it?