It’s because the game that gets a lot of installs for cheap (simple, hyper-casual) is not the game that makes a lot of money (deep power based meta progression, complex).

In other words: It is more profitable to cheat and get a few paying customers than to try and be honest in marketing.

Everyone is trying to buy users for less money (cost per install) than they bring in (average lifetime value) which is insanely difficult. The market is very competitive and just few top games / companies get a lions share of the money.

Source: I work in the mobile game industry