No orientation API so impossible to make games and other experiences that require a certain orientation
No WebXR (though Apple will allow it on Vision Pro)
No support for ResizeObvserver devicePixelContentBoxSize so impossible to get correct rendering reguardless of user's zoom level.
No simple PWA installation. Requires an obscure incantation that only expert users know.
That's just a few off the top of my head.
Yes, I know all the comments will be about how they don't want those features. That's really irrelevant. Allow them to be turned off. Require permissions. Those features have been shipping on other OSes, Desktop and Mobile for > 5 years and the world hasn't ended.
That said, the only plugins I use are ad blockers, so maybe I’m missing something.
Even if that's an edge case, it's why having only one engine is pathological. Maybe Safari iOS works fine for you. Not for me. I don't want rationalization on why it's not Apple's fault, or somehow not Safari's fault, or "they'll fix it one day", or "I'm doing it wrong", or all the fanboy-talk that sounds like the enabling relative of an alcoholic. Don't care. I should be able to switch for even the most frivolous reason. Maybe I don't like that it doesn't render every website in pink.
It's like having only one type of chocolate in existence. This was never normal.