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.