While I get what you're saying, I only find this drop in quality on really cheap Bluetooth headphones/headsets. I have tried 2 "high-end" wireless headphones (1 of which are my AirPods that I own) and I find no downsampling or quality loss that's noticeable.
It's real & severe downsampling, and incredibly noticeable.
Bluetooth 5 should have the bandwidth to solve this problem.