Indeed, it must be tempting for many smaller manufacturers to give up the player sector to those companies able to manufacture in huge volumes, and concentrate on the rest of the audio/video chain.
Trouble is, the AV amp/receiver is becoming very complex these days, with multiple layers of licences involved, so making a new product in this sector must be pretty daunting for many a company, especially when the 'big boys' keep moving the goalposts so swiftly and regularly.
But then, of course, the smaller companies must feel pressure from established customers and retailers to offer an 'end to end' solution, which may corner them into making products on which they're going to spend huge development effort, and see little return.