Not so sure that's true, IntenseDegree. I already gave you 22 individual names of non-Mystians in my post + all the Nancy Drews (not my favorites) + all the Legend games. And then we have the FMV detective games, like In the First Degree, Blue Heat, SFPD, etcetera.
There used to be a list of all the Mystian 1st-person adventures at JustAdventure. Don't know if it's still around. Some 50 games, if my memory serves me well. Colpet might know, she's into Mystian adventures.
Not many new ones coming out these days. Bracken Tor this year, that's about it.