Microsoft had the problem a few years ago with bundling their Internet Explorer on Windows (and making it hard for the competition to have a chance). For Apple, the situation is a bit easier, as they don't allow any third party app stores at all, so any competition would probably encourage their users to break Apples 'Terms of Use', which in turn would make a lawsuit even more difficult.
In my opinion, platform providers should be obliged to open their platform for all kinds of third-party services & tools but I am sure, Apple/Google/Microsoft/etc. will find other ways to discriminate others on their platform and push their services.
1) the ability to install their own apps, no restrictions (IF approved by owner)
2) the ability to get apps from wherever they want
I would be much happier.
You might argue Google is dominant in advertising worldwide, but Facebook is a contender in many countries (e.g. in the Philippines, Facebook is "the internet" as an approximation).
If you want to pick and choose subsectors, I am sure we could pick markets where mobile is one of the words and the second word is also something Apple absolutely dominates.
The world is a big place to make sweeping generalisations about.
Edit: parent article is about Portugal, not the world. A friend said to me: working in antitrust, on either side, a key is defining the market.
Having a smaller market share doesn't mean you can get away with breaking the law.