I'm not going to pay $10 for an app I can't transfer to another device. As long as our phones are disposable so too are our apps. And I don't pay top dollar for garbage.
Do they run on Android? Windows? Linux? My point is that they're locked to an ecosystem I'll never be able to leave if I heavily invest in. I minimize app purchases for this reason. I don't want my digital life to be tied to a particular company or brand, and I run free software as much as possible because of this.