Sites like Hulu and Spotify predominately use web analytics to gauge their audience in order to sell advertising, not to make their sites better. That may be a by-product, but that's not driving their analytics usage.
Additionally, cross-site tracking isn't used for feature/usage tracking. It's used for highly targeted advertising.
My point was the "shattering advantages" are really advantages for advertisers, not web designers.
This technique wasn't developed with web designers in mind, so let's be clear about that.
Spotify has perhaps the least targeted ads i've ever seen/heard on any media source. We listen to indie rock and classics all day only to hear the latest Jason Derulo clip several times a day as an advertisement. That's clearly not targeted in any way. There is 0% chance we will do anything but hate the song as a result of this ad. None of the ads are in any way relevant or appear to be targeted by anything more accurate than "18-35 demographic, serve them ads for shitpop" without discretion:
Spotify dont sell enough ads to make targetting feasible. They play you all their inventory. Until you buy a subscription because it is too annoying...
It's used to allow publishers to make more money from their consumers through advertising.