Show me this put together beige box, and I will show you a machine with missing features found in the Mac Pro. Then you will say, "I didn't want that stuff, I would never use it," but when added in, the prices will be within a close margin.
I do see your point, but even if that's so, the problem of Apple hardware inaccessibility to an average computer hardware buyer cannot be considered as "resolved" or "unavoidable", but only pivots from the circumstance of "Apple forcing high profit margins on hardware buyers" to "Apple forcing a set of (unwanted, yet costly) hardware features on hardware buyers" (through the lack of appropriately varied hardware models and hardware configuration options).
Which is too bad, because if Apple hardware was appropriately inexpensive while delivering the features that I do care about, I would probably consider switching to their hardware and macOS as my primary O/S. (... But then again, maybe not - I really like the latest Linux KDE/Plasma.)