2 million apps / 10 years = 547 new apps every day for the last 10 years. And of course the number of apps coming out today is far greater than it was 10 years ago so it's actually more like 1000 apps a day right now.
Steam has the same issue. Steam was around 8k new games in 2017. That's 21 new games per day, 153 a week, 666 a month. No one has time for that many games.
What would Steam do to suddenly get all those games to make a salaries for every indie that put stuff up? There's really nothing they can do. There's just too many games. At most Steam could go back to restricting the market. That wouldn't raise anyone's odds, it would just make invisible all the people that tried and failed to get on the market.
It's the same story with books. Apart from rare mega hits like Harry Potter, the bread and butter of the paperback world is least common denominator stuff like Danielle Steel and Nora Roberts.
I don't think we can blame Valve here. This has happened across all forms of media. There is too much content and not enough time.
2 guys and a mic, without Youtube, would just be a self-funded hobby to show your friends and family, maybe enter some indie film shows, maybe help get a job in advertising or local TV with your portfolio. With Youtube, they might get a million subscribers and make on the order of $10,000 per year from what would otherwise be just a hobby! And there are on the order of 10,000 such channels with 1 million subscribers.
Now, you can say what you like about how Youtube treats the other 97% of channels with far less viewership - but there's a lot fewer than 10,000 channels on mainstream TV.
It's the same in game development, mobile app stores, music, sports, and a lot of other fields. The marketplace is open to a lot of people who really want in to get their chance at the top. It's hard to earn a living wage from doing the work when you're competing with people who are willing to earn less than a living wage.