I think you're mixing up commercialized MMA with more traditionally-attuned martial artists who master useful methods from a variety of backgrounds to become their personal best at fighting arts and skills. These latter individuals are also MMA, but I wouldn't dump them in the same pot as the jamokes who tussle for $ as sport-style competition on TV.
I agree with you. Ironically, the same thing happens with respect to aikido: people see one or two Japanese shihan (or their students, or their students' students), often in a seminar rather than in daily training, and draw broad conclusions about the art. As some sage said, "All generalizations are false."