I don't think most people care about Raspberry Pi options. Not that a lot don't use it and find it fun, I just think the average consumer isn't interested in figuring it all out. Especially if there are a ton of options, variations, etc. associated with it. But, it is one option, of many, which provides streaming audio services to the home and individual.
Also, you have all the devices which connect directly to your phone and allow audio streaming from a phone. You have phones which have better internals for better audio quality playback. You also have the long list of audio only streaming devices which are out there including a ton of AV receivers with integrated streaming apps and wireless connectivity to phones and network storage.
The list of options which cost under $1,000 is massive. There are even many options under $100. I certainly wouldn't expect Linn-like performance from the cheapest solutions, but I would expect that for 99% of those who would buy a Linn system, they may be hard pressed to tell the difference.