A straw man in your favor, maybe. Shall we compare the 100 least popular of each store?

Those are more likely to be outright malware on Play.

The popularity in app stores has no bearing. Some problem apps can be on no store, just locally installed. This has been well covered in the past and you are playing catch up. It’s about abusive household members who spy on their grown children, siblings, roommates, girlfriends, parents, etc. with apps they install on their devices if given a route to do so.

The sideloading change doesn't protect against abusive household members, though. Simple lock screen hygiene and periodic reminders about invasive permissions (e.g. accessibility & location) would do more. And let us not even pretend that is the true motivation for the change. An incidental consequence that you find defensible is simply that.