Why should a web app that you've manually installed (added to your home screen) be more restricted than when it's accessed via Safari? The feature/bug argument

Why should a web app that you've manually installed (added to your home screen) be more restricted than when it's accessed via Safari? The feature/bug argument doesn't really apply here - your preference is not the same as everyone else's, and your worst case scenario shouldn't prevent valid uses of the same technology. Especially when it's already something the user has chosen to install.