"Prosumer and uses built-in HD graphics?"
"Professionals are those with more demands, mainly in multimedia performance"
People wrongly think of PRO as automatically meaning Photoshop, Premiere and GPGPU compute.
There are lots of guys using laptops to write software and only 0.01% of them need a GPGPU, the rest only need (in this order) a fast SSD, 16GB+ RAM and an i7 HQ. For these guys, a dGPU or a calibrated LCD won't speed up their compile time or the locally-installed Oracle server.
Another example: architects spend 99% of their time drawing and they like 4k screens for their fine lines but color accuracy isn't important, nor huge amounts of RAM, nor how fast the processor is. Common rendering modules for their software can use some GPGPU but architects render those models at the best quality only once every few days, normally they do fast-renders which take 3s anyway, is nothing to benefit from having an expensive NVidia card.
For my father in law, PRO is a 17" laptop with a 4K screen no matter how lame (color-wise) or how slow as his business is AutoCAD-based, topography.
So PRO doesn't mean only multimedia.