Apple just kicked Fortnite off the App Store

Imagine if Microsoft did this on PCs. a) prohibiting the installation of non-windows store software (sideloading) and b) insisting that all purchases done via apps give them a 30% cut. I think this is a ridiculous practice on the behalf of Apple.

Even worse. Imagine if the World Wide Web was not open and you had to go through a closed WWW like AOL and websites were "under review" by the providers and would take a 30% cut of your revenues or clicks on your web app or subscription service and websites require going only through that provider.

Thank goodness that wasn't the case.

It could be the case if AMP grows dominant; given the market share of Google Search, it could be enough to create a controlled (er, "curated") web in a similar spirit.

AMP isn't enforced though. You can say 'not yet' or 'it's kind of the same' but that applies for a lot of standards.

It's enforced through visibility / rankings in Google Search results.

https://developers.google.com/search/docs/guides/about-amp

Isn't there a term for using dominance in one market to compel behavior in another?

Your link doesn't say that Google forces AMP on publishers. It shows that Google displays an icon next to AMP results for mobile searches to indicate the page is mobile friendly. Bing does the exact same thing: https://blogs.bing.com/Webmaster-Blog/September-2018/Introdu...

This is not enforcing AMP on publishers in the results, and the argument that it is by using icons falls under the 'it's kind of the same' category.

It says they use site speed in ranking, and, well, I'm sure it would come as no surprise if Google's (largely) having served a page/site increases the speed just enough.