A quick solution on Apple's part could be to add an easy to use domain blocker as part of there tracking blockers for Safari. Could be buried in the safari settings pages, but with a toggle to apply at an OS level.

It's a money game and Apple could totally crack down it, but they won't. They may long term but they take cowardly slow steps like everyone else does.

So exactly how much money does Apple make from free apps?

If Apple wanted to make money , it should make it harder for advertising supported apps to make money and force apps to either not exist or get people to pay for them.

I would be okay with that.

I guess Apple will have to weigh whether they'll want to tolerate the Fb app on iOS, but more probably they have a deal with Fb (else they would've kicked them out already). Considering Fb is said to be the main portal for "the web" as a Fb user might see it (which I find still very hard to believe for a number of reasons), if the Fb app (or worse, WhatsApp) isn't on iOS, with Safari and FF already blocking most tracking on facebook.com, Fb might block Apple devices altogether, and Apple might or might not stand to loose in device sales, depending on the intersection of Apple's with Fb's target demographic. If it were only for Spotify (which is a direct competitor to Apple Music), they'll have to weigh whether them kicking Spotify out will be seen as anti-competitive vs having a good excuse for eliminating a competitor on their own platform. But maybe my speculations are way off, and Apple will just tell Fb to fix their shit.

I would think that Spotify would want to remove the SDK. It doesn’t need the marketing tie ins anymore and it doesn’t use FB for advertising.