No, that's not right.
Brake fade is caused by the inability to control heat buildup, and heat gets EVERYWHERE on a braking system, effecting all brake components....
Cheap brakes can cause all sorts of problems.
a) Two piece caliper flex can reduce braking force
b) Piston size, quantity and position can cause uneven pad pressure, causing uneven pad wear and brake force
c) Poor piston machining and seal design unable to prevent stiction in bad weather and salt buildup, this can cause brakes to sieze against the rotor and warp discs
d) Poor caliper design can retain heat, rather than disperse it
e) Cheap Brake Rotor material can warp easily under sudden extreme heat transfer or poor running in process
f) Cheap Pad material can glaze and provide poor resistance reducing braking power
g) Cheap Brake fluid can boil and not handle heat buildup causing gas separation from water molecules (causing fade)
h) Rubber brake hoses can expand under heat generated increasing volumetric space for fluid, reducing braking force
This isn't MotoGP stuff either, heavy bikes with a heavy load on a steep slope with regular braking will cause the brakes to have to deal with a lot of heat.
Good luck on your mountain bike brakes
Time will tell....