I don't know about that. One provider who I saw at a bodyrub agency incall was a girl who I dragged out of the place for private outcalls, simply because she enjoyed my pleasuring her (first with fingers, then licking around but not on the privates). That led to her coming to my place, and although she stated no FS, that's exactly what happened.
She was supposed to be there an hour, stayed three. She was supposed to not do FS, she did. And she never charged me more. Still doesn't to this day, and our sessions can last a full day or the weekend.
I'm guessing if I didn't pleasure her, the rest wouldn't have happened. It doesn't always happen, but sometimes it does. And I like pleasuring them for the sake of it. It doesn't have to be about me. I've gone to a place and just pleasured the woman during the session when I felt like it.
Maybe I'm weird, though...