Another big factor is developer engine knowledge. It’s expensive to train developers on a new or unpopular engine when you can hire plenty of devs who are already familiar with a popular engine like Unreal. 343i continues to have this issue with Halo Infinite running on their Slipspace engine, which is why (IIRC) they’re switching to Unreal for future games.
I miss the specific game subs, like Elden Ring, Satisfactory, Hades, etc. I don’t think we have the population yet to have subs like these with lots of content posted each day.