I’m exactly on this bandwagon too.
I would rather pay, say $13 for GoodNotes 5 from the AppStore instead of $10ish outside and get the security, sync between devices, family sharing, Mac/iOS/iPadOS all in one shot, auto updates, change/upgrade/repair device and it’s still magically there like if it never went away, etc etc etc.... same with ProCreate, Photoshop and others.
However, how could this be resolved? There must be a way to keep everybody happy? Devs and customers and tinkering users alike?
Maybe allowing the use of apps installed from everywhere but shifting accountability in that case? i.e refunds have to be handled on your own, if an user’s bank account gets hacked can’t blame Apple for malware gotten from dubious software, so on and so forth...
Would that make sense?