On iOS, all web apps launched from the home screen have to execute within a webkit rendering context.
For developers trying to exist outside walled gardens the home screen is the fulcrum that enforces Apple's monopoly.
I've read about how the EU is forcing apple to allow rendering engines other then webkit. My hope is that we can hold the line and demand these rendering engines have access to the home screen.
For me, this is the only sure path to a fair marketplace.