Earlier quoted context omitted.
it makes more sense to do that processing once in the datacenter. Since Apple is all about on-device processing with so many of its features, going back-and-forth to the data center doesn't seem to be its style these days. That's more of a Google thing. And no one can accuse Apple of telling its advertisers that you start your day with Funky Cold Medina.
There's a reason Apple's preferring on-device processing: user privacy. This doesn't make sense for music (stems, lyrics) since it's not listener's data.
It makes it so you have to buy new devices sooner.
The privacy thing is a nice side-benefit and PR thing, but let's be realistic here.
EDIT: Just to remind everyone, we are literally in a thread about a new device feature that is trivial to do in the cloud, which Apple chooses to do on-device, which makes it only a feature for its newest generation of products...