I agree with you - but it is also a lot to expect from people.

For example - My house-mates and I got drunk last weekend and very inebriatedly one of the males went on about what he had tried in the bedroom. and he mentioned something about bdsm etc. But he doesn't actually mean bdsm - he means kinky sex. Because to most people that is what bdsm is.

Now for myself it is very much about sex (lol its the novelty) but I do know the difference - it makes me feel so differently whether I am in the life-style with someone or whether I'm having kinky sex with someone. But I do think it would be difficult to explain to someone like my housemate.