Apple still lives in its walled garden and defends it vociferously, but I would argue they have made the correct design tradeoffs for their business.
The issue is that this in no way requires soldered memory. CAMM2 supports speeds up to 9600 MT/s. You can get over 300 GB/s from two CAMM2 sockets.
It's an acceptable approach for iPad-level stuff, but for professional workstations and desktops it's not competitive.