I think its because their reddit app is shit, they got an initial large influx of users because they were giving away a free reddit gold the first time you used it with an account so it shows lots of installs on the store but their number of active users must be tiny now. There's about 20 apps better than theirs available before and after their one came out and they pushed too hard making it look awful on mobile browsers and kept taking up a quarter of the screen space trying to get you to use their app.

They have forced this horrid mobile style layout as their main default now. They don't seem to want to accept that RES and these other mobile apps are what fix their site and give the features they had nearly a decade to offer themselves but didn't.