I'm not sure it's fair to equate smartphones to general computing platforms, regardless of the marketing speak surrounding the newest iPads.

Personally, I like iPhones precisely because they're not general purpose platforms. I'm also not sure the phrase "general computing platform" can even be well-defined in the era of "smart" everything.

One definition may be that you can use the device to write and compile all the programs it uses (any part of the OS, including the kernel itself), so that you don't need anything else. Kind of like a self-hosting compiler.

Not that you'd want to, but if you decided to do it, the option would be readily available.

Then modern game consoles and s smartphones qualify as well, they definitely have the resources to compile everything & only artificial limitations introduced by the manufacturers prevent that - which is sad & limits their potential.