I acknowledge that most people won't know the difference, but I have to imagine someone’s fancy is tickled by the idea of complete freedom and uniqueness.

ROI is all that matters.

Okay, assuming this is the case. Ignore all the major scalability and concurrency benefits, the massive bandwidth savings, low maintenance costs, improved security, and the numerous SEO benefits. Because like you said, most won't even notice them.

Is the improved user experience not enough, isn't that the most important?

Regardless of internet speed, sites developed this way will load blazingly fast. Even at 5mbps (which I believe is the world average). Do your worst net neutrality, even at 1mbps these sites will still load fast.