One is focused on Quality-of-Life and features, the other is a vehicle for shoving as much telemetry, ads and tracking down the user's throat as is humanly possible.

Reddit could've most likely made a killing off of allowing third-party apps to operate as normal for users that had Reddit Gold, for instance. It would have been a mostly-acceptable middle ground in my view. Except they decided to instead double down on presenting wholly unreasonable licensing terms to third-party app developers.

The intent as far as I can tell was never to allow third-party apps on the ecosystem - it was to extinguish the third-party app ecosystem under the pretense of there being an alternative. The forced first-party app is critical for them to milk out as much money as they can from advertisers etc ahead of the IPO.