There is no useful purpose of letting people know. They won't benefit from knowing it. It's none of their business.
That is also true. I don't bring up the subject myself. But if a friend or family member begins a discussion of non-vanilla sexual practices, then I tell the truth.
An example, from 2013. My brother and sister-in-law and I were sitting in a restaurant having already ordered dinner waiting for it to be served.
Below, I will use B for my brother's name, S for my sister-in-law, and Z for the name I use when talking about Goddess Shelly with family.
B: S is reading
50 Shades of Grey. I don't understand why it is so popular.
Me: It is one of the few BDSM novels that has crossed over into the mainstream.
B: What is BDSM?
Me: BD stands for bondage & discipline, DS stands for domination and submission, and SM stands for sadism & masochism. When you were in college, the BDSM novel that became popular and known was
The Story of O by Pauline Reage.
B: I read that one,
The Story of O. I don't understand why people enjoy that stuff.
Me: It can be fun with the right partner. Z and I do lots of kinky things. Nothing that leaves scars or draws blood, but definitely kinky.
S: Really?
Me: Yes. In fact, several times when I said I would be in Philadelphia for the weekend visiting Z's friends, we were attending a kinky convention there.
S: What kind of stuff do they do at a convention like that?
Me: Bondage, certainly. But not to be branded or whipped after being tied up, just to be tickled without mercy.
S: Ah.
Me: If you don't do anything kinky at all, then members of the BDSM community would call you "vanilla." That is an insult, actually.
B: I see. So you and Z are not vanilla, even though you don't do branding and whipping?
Me: Exactly.
At that point the food was delivered.
No big deal, I told the truth as needed in the conversation and didn't dwell on it.