I think it would be naive to think that their stance is more than a marketing strategy. But it does mean they take a stronger stance on user data than others. They at least have incentives to protect user data so they can bash Google about privacy invasion in their marketing.

China and other oppressive regimes tend to be where the marketing gets in conflict with the law and China has a lot of leverage on any major electronics manufacturer.

Still a capitalist business so ideology or ethics don't really factor into it.

I think it is correct that Apple could benefit in amrketing from having no ad systems on their platforms. Not convinced it would be net positive for them though.