I'm going to go back to the OP....
To be perfectly honest, Whitney was never the sort of music I wanted to sing, but was just about the ONLY pop style I COULD emulate as a teenager. I wanted desperately to be Joan Jett (or anyone else who could wail in a chest voice) and it wasn't going to happen.
I have a serious vibrato that most of you can attest to-- is it "natural"? I think so. It's what comes out of my mouth first and foremost and how I can sing most easily. Meaning, If I allow the full-on vibrato operatic style, it's literally EASIER for me to sing. It's my default mode. I usually use it when learning notes, then when I've got that down, I can think about how I want to use or not use it. I don't think, in my case, that it's a cheat, or a cover up (not being defensive, just stating).
However.... And this is years of lessons talking, years of thinking about turning it on, turning it off.... It comes from neither my vocal chords or my diaphragm. I feel the vibrato forming at the very back of the soft palette... It's the place from which my teachers INSISTED That I pretend there was a string attached and pulling me to the ceiling. Really. A string running from my spine, through the back of my head and up to the sky. She was always "pulling me up" by this imaginary string as I sang. Sometimes she did away with the niceties of a pretend string and just grabbed a few strands of my hair and used that, instead. Always fun in the middle of high Ab. "Send the sound out the top of your head," she'd say, making big, circling gestures with her hands above her head, signaling to let the vibrato flow out the back, Over the top, to the ceiling.
On the other hand, "Pop" vocals to me, are the opposite. Shut it all down. Don't let it move. Thin it out on the soft palate. make it Airier, Breathier. I can't tell you how people belt it all out in a chest voice. I HAVE one, but it's very limited. Ive found that Im always always always flat when I try to "sing big" with a chest voice. On the other hand, I have a huge range when using the classical voice, and I'm getting better at the breathy stuff. I've been practicing.
Whereas classical singing happens (with ME) with a completely open soft palette and throat, I really have to concentrate to make a pop vocal. It takes so much more control and concentration for me. And, I usually get it wrong.
A "Jaw" vibrato, I'd consider bad classical technique. But pop music is different. In pop, nearly anything goes. But... you still need to use your diaphragm, and if you poke your chin into the air to "reach" the note, you are straining, and going to hurt yourself. Keep your chin down.
Edit to add: I don't remember ever learning how to produce a vibrato, either. I learned how to control it, yes, but that's a different thing.