When you pass the checkride and get typed in the Ejet with Mesa, why do they limit you to "ERJ-170 ERJ-190 CIRC. APCH. VMC ONLY"?

I am PIC Typed (F/O) in 2 aircraft with another company and never got that, or any, limitations.
I was thinking about going to Mesa to be home based, and I just found this out with a friend who recently got typed there.

What is that all about???