Anywhere Apple wouldn't trust a third party is a place it should not trust itself either.

It doesn't even have to be arbitrary third parties, it can be Apple's chosen third parties. But they'll choose nobody, because they love lock-in too much, and they'll tell the rubes that it can't be done or it's too hard. That's just bullshit, and they know it. They do it to lock out competitors, so they alone can juice their existing users.

The only thing that can open up Apple is regulation -- and as we've seen in with Apple's spiteful attempts at compliance with EU DMA rulings, it makes up arbitrary criteria calculated to maximally lock out and frustrate business rivals. It's like it's trying to come up with a compliance solution that the EU might accept but would result in as few competitors as possible able to actually use it, ideally zero.