The iPhone is a fully functional miniature computer that also makes phone calls.
The NES was a fully functional computer that also played video games. Except it wasn't because of DRM. Same problem the iphone has. No walled garden is a fully functional computer. Macs can take unapproved third party software so they're the only Apple product that qualifies as a fully functional computer, unjailbroken iphones, ipads and ipods can't so they don't.