The mx250 is not a "middle class DGPU" because there is no class below it. It's Nvidia's weakest dedicated graphics card they continue to sell, and it's a pretty terrible point of comparison. A better example would be the GTX 1060, a middle-class dedicated GPU that made it's way into many budget gaming laptops 7 years ago. It is faster than the M1's GPU.

The Mac has a very dedicated audience of video and design professionals who are going to be left empty-handed here, even if they double or triple the amount of GPU cores in the SOC.