There's being deaf, and then there's being Deaf. Some people can't hear; some people can't hear and are part of a well-defined and somewhat insular community of capital-D Deaf folk. The Deaf people have all kinds of social conventions and institutions that the merely deaf don't.
So Wednesday's strained analogy is to kinkiness versus the kink community. Some people just like to play dominance and/or pain games with their partners; some people are part of The Kink Community. I'm somewhere in the middle; I know about the community and I've had many contacts with it but I don't think I'm really a part of it. I don't have a ton of kinky friends, I don't always get all the fiddly details of kink etiquette right, and I often do "bedroom play" rather than formal "scenes."
I suspect that there's a huuuuge number of non-community kinksters out there; after all, the urge to get hit during sex and the urge to talk about it in a Denny's full of black-t-shirted geeks are rather separate things. Also I've noticed that when you get a totally vanilla-identified person's pants off, roughly a third of the time they'll turn out to be into dominance and/or pain, whether they believe it's "that weird BDSM shit" or not.
This is unfortunate in some ways--information about safe and effective techniques doesn't get disseminated to unaffiliated kinksters, nor does the "you are not crazy, you do not need to repress this" message. (The Internet helps some, but it also spreads a shitload of misinformation.) A kinky person who doesn't know about the community is going to spend a lot of time reinventing the wheel. But it's inevitable and understandable that most people who like weird shit in the bedroom would have no desire to identify themselves with it anywhere else.
The kink community is cool in many ways, but they are not kink. For each person at a leather party or convention, there are ten at home alone or with their partner, just doing their thing. For good and ill, "how things are in Kinkland" concepts only apply in Kinkland, not everywhere bruises are traded.