I am a developer and I agree with you.

A blacklist isn’t a good approach on its own - you could never predict all the possible apps you might need to block. But it is a perfectly reasonable failsafe for “content rating” and would probably even provide some valuable app-level feedback for the platform to use to check up on apps that are gaming their rating.

A whitelist approach is a reasonable overall approach and to some extent I guess you can implement this by allowing any content rating but requiring approval to install an app. At least I think you could do it this way. Like I said the settings are a bloody mess and hard to use so I’m only ever 80% sure of what’s actually happening.