What is the argument against, and dangers, of simply maintaining their app store where they continue their strict quality control & take the fees, while also al

What is the argument against, and dangers, of simply maintaining their app store where they continue their strict quality control & take the fees, while also allowing 3rd party app stores? App devs can choose to participate in Apple's store and pay fee or not or both. 3p allows users to load any apps at their own risk. Put a permissions popup explaining the danger. Maybe it would open up more jailbreaking. Don't allow drive by downloads, users would have to download the 3rd party stores from the app store. Probably only the most determined / technical users would load a 3p store thus protecting the majority