Apple's reasoning is that browser engines need JIT to run JS with acceptable performance, but if they were to give apps JIT capabilities, that would significantly open up the attack surface.

Apple has an ads unit, there have been multiple other times when they have shown that user privacy is a thing that really only applies to other companies.

Don't know if serious or not, but I'll bite.

Apple was in deep troubles when IE was all the rage, you needed IE to access your bank's site, your company's intranet, so many site that were strictly IE only. Microsoft gifting them an implementation of IE was a mild grace, but still wasn't enough. Not having a browser compatible with 99% of the web was an issue pushing people away from Macs.

They learned their lesson, and used their advantage in the mobile market to make sure no other browser ever puts them in a similar position.

Google has a slightly different issue, in that for instance a strongly privacy focus/ad blocking browser taking the android world by storm is nothing good for them.

Firefox and Chrome accounted for a third of browser marker share when the iPhone came out. It came out with no App Store, and there was no guarantee MS would develop IE for iOS.

> I can't think of another reason they'd limit browser engines.

Apple doesn't trust third party developers when it comes to running code that Apple has not vetted in advance.