Some people are missing the forest for the trees here
Having a businesses app on your phone is better regular advertising than anything they could ever pay for.
They just want an excuse to make you look at their logo and think about their business as regularly as possible
Spez explicitly promised they wouldn't get rid of old reddit.
Which I took to mean they intend to ruin it by cramming all the shitty new features into it and taking away the things it does better.
Edit: I don't trust spez lmao I just think what he said might be a hint for how they will fuck reddit up going forward