The fact that the app is still so bad after so much time has gone by indicates that it is the desired product that the company wants to offer. And after realizing that they were still losing users to better competitors, their solution was to destroy the ability to compete in the first place rather than improve the product.

They like the app as-is, with all of the terrible performance and UX that goes along with it. The reason behind that is because they're getting user engagement metrics and other telemetry data, more control over ad delivery and the content users see (including astroturfed sponsored Reddit content), and more monetization.

Third party apps, like Apollo and AlienBlue before it, cared about providing a good user experience. It just happens that users typically prefer experiences that aren't trying to capitalize their every interaction, and companies take that personally.