If you explore the house, jip-hop, funky etc styles .... you'll find that lots of these are the basis for the smooth jazz style.
Around Philly we have a terrific "real" jazz station from my Alma Mater ( Temple U )and many people don't buy into the "smooth" concept as jazz at all. Still...it's pleasing to the ear and there are lots of pretty, melodic interpretations to sample.

Is "Smooth" jazz really jazz? Who knows. That's a topic for another day, but the basic rhythms are pretty modern in concept. It's just the sounds that keep it smooth I think. Lots of electric pianos, thick pads, and solo wind instruments. Not too many irritating guitar leads or harsh sax honking. It's eazy on the ears.