I have written some integrations against altinn, the Norwegian government's portal for basically anything official. Getting approval for a scope there is a process, as well it should be. If I write an app that lets users send construction applications to the local municipality on the user's behalf, do you think I can just sneak in a request for permission to change the user's address, name and bank account registrations as well? No. There are scopes for that (I assume), but my app won't get to request them, no matter how much the user would be willing to give them.
And "caveat emptor" is not the threat model you can get away with on the web. Sure, it would be great for me as a dev if I could just disavow responsibility for cross site scripting attacks and other attempts to misuse the user's credentials. But I'm a user too, and it would NOT be fun as a user.