Hah, good one.
All of the platforms make most of their money from digital market fees. Consoles themselves are loss-leaders I believe (at least they used to be). Each of them wants you to be stuck in their platform. Steam has the weakest grip of them all, because you can just go buy your games from another store, but luckily for them, the only other store that's even halfway decent is GOG.
There's very little that can be done about the whole damn thing unless either the EU or the US decides to force console manufacturers to open up their platforms to 3rd party stores. Which, to be clear, I would absolutely love. But I doubt it's going to happen.