If it's merely "yet another smartphone API" then why is bundling your own prohibited? This has nothing to do with (warranted) complaints about the state of browser complexity and resource usage. It's anticompetitive because you literally aren't permitted to compete with them.
An example, hopefully valid but I didn't double check. Android provides a file system API but presumably I can do FUSE-type stuff in an app without it getting banned from the Play store, right? Maybe "mount" an iso image and let the user browse around in it?
“It's anticompetitive because you literally aren't permitted to compete with them.”
That’s not what anti-competitive legislation says. You are making a cute argument using a slogan term and ignoring the definitions within the statutes.
The internals of a browser aren’t significant when it comes to product differentiation. They are significant when it comes to user-impacting features like battery life, security of data on the device outside of your app, and reasonable app sizes. These are the arguments I have seen that defend AAPL and their walled garden.
Anti-competition legislation is prosecuted based on whether prices for the end user are impacted, not whether there is freedom for a developer to rewrite some internal API that Apple already supplied.
There are much better arguments for anti-competitive behavior against Apple than the proprietary browser engine.
An example, hopefully valid but I didn't double check. Android provides a file system API but presumably I can do FUSE-type stuff in an app without it getting banned from the Play store, right? Maybe "mount" an iso image and let the user browse around in it?