iOS is, for its purpose.
that can use the large screen and has access to the terminal and file system.
MS tried that with WinCE, for the file system, and it was a bloody mess as far as usability.
It's powerful enough to be an entire computer, so give us the option to use it as one.
It depends on what you define as use it as one. The iPhone with iOS can do what most users do with a computer - email, web, shop, etc.
If you make an Ultra and it comes with Mac OS so that I can plug it into a 4k monitor and use it with a mouse and keyboard to do regular MacOS things (and with iOS "mode" for commuting / bed use, etc) then I will order it the moment it goes on sale...
Others have tried this and failed.
...and then promptly duck away from the airborne porcine hordes...
I agree that isn't happening.
Apple filed some patents a while ago of doing something like that. Basically using the iPhone to dock into other devices. Like an iMac “shell” or a laptop “shell” whereas the shells would basically turn it into a full fledged computer by adding bigger screen, physical keyboards, pointing devices, ports, additional storage etc. I think Samsung also experimented with it but it didn’t take off. Withe the increase in power now of the iPhones I think it still might be worth a look although even though Apple always denies it, they would be afraid of it canibilizing full computer sales.
Here's the problem:
People would expect it to perform like a real computer, with graphics, video, calculation speeds like a Mac; as well as having enough storage to hold their work.
The A series chip is nowhere near as powerful as the M series powering Macs. Thermals could also be an issue under load, resulting in throttling and even further reducing performance. You'd wind up with either a slow Mac or a MacOS Lite which people would complain was crippled due to some vast conspiracy by Apple and Tim Cook.
Then there is the issue of battery life. I doubt the iPhone's battery could handle the load of being used as a computer so one of the key advantages, portability, is lost since it would not be usable as a laptop.
You could make a dock with increased storage, GPU, etc but the price would quickly approach a Mac while not being s powerful. In the end, it wouldn't cannibalize sales but just be another Pippen.