My argument is we regulate these companies and not others because these are important to society, yes. Same as we regulate phone companies or the internet.
We can't allow two global multinationals to gatekeep this much of our modern lives and simply do nothing about it. Or we could, but we don't want to.
Apple and Google can leave the market if they don't like the rules.
Doesn't that argument prove too much? I can think of several things that are much more important to society but regulated less. For example, books are important to society. Should the government dictate what books publishers are allowed to publish? After all, certain ideas are extremely corrosive to society and should be discouraged. (I can think of a few religious texts that might fall under that umbrella.) Or what about the opposite? Amazon doesn't sell certain books on its Kindle platform. Just like Apple and the iPhone, shouldn't Amazon be forced to support third party stores for the Kindle?
Apple's app store isn't nearly as important to society as books, but the EU regulates it much more. That makes me think that the driving factor behind these particular regulations is not importance to society.
The government isn't dictating which books are allowed to be published, it's arguing (amongst other things) that self publishing books should be possible, which it is.
Being a successful smartphone manufacturer (or a smartphone OS manufacturer), shouldn't give you a monopoly on software distribution, that's the entire point.
And even the Kindle, which doesn't have the market relevance of iOS, isn't as locked down as iOS: the Kindle does support reading ebooks from other sources, they just don't support DRM from other stores.
We can't allow two global multinationals to gatekeep this much of our modern lives and simply do nothing about it. Or we could, but we don't want to.
Apple and Google can leave the market if they don't like the rules.