Macs have never been about highest possible performance at any price point. But there is a niche where people want a very fast computer that is quit and not too ugly (and who can find their apps on macOS).
Putting two GPUS in a tight spot and the limitations of the time basically doomed it to failure but now we have much better data rates and better iGPUs.
It's a valid approach in theory but it seems pretty clear that the market hasn't embraced it. The most recent Mac Pro recognized that people weren't embracing it, but really, are there many (or any?) 3P cards that can be plugged into a Mac Pro?
You can build/get quiet PCs too. Theres a whole PC accessory company called be quiet! even. And there's some very nice IMO cases that look better than the Mac Studio or Pro...