Comment by TheDong

The extension ecosystem of browsers is pretty important though, and that is tied to the rendering engine.

On Android, I can install firefox-for-android and run ublock origin to no longer see ads on websites.

On iOS, that's not possible. Apple prevents mozilla from shipping a browser capable of running firefox addons.

This is a case where Apple's policies are hampering security since, well, blocking ads on the web is the thing has had the single largest positive impact on security for my elderly relatives. Giving them ublock origin stopped them from clicking on a ridiculous number of scammy ads and popups.