I never claimed they literally can't do productive work, they're just not built to do it.
Touch interfaces and the corresponding on-screen keyboards are good enough for short texts but even writing a medium-sized email is a pain in the bottom compared to the full-size keyboards computers come with. Autocorrection systems make it less painful, but they're absolutely useless when writing formal languages like code or math and since their capabilities are limited, natural language writing isn't as easy as with a hardware keyboard either.
There's a reason for the name of the category "consumer electronics". They're meant to be good at consuming media, not producing it, that's what the workstation is for.
There's a slight difference though. A tablet is meant to be carried around and an external keyboard kind of ruins this, though I admit there've been solutions to this which didn't completely suck.
A workstation is stationary, so mobility isn't an issue and usually the keyboard comes with the workstation anyway.
And on a sidenote, what you're basically saying is that it's easier to be productive when you have any means of I/O at all than when you haven't.
Doesn't change a thing about what those devices are focused on though.
Touch interfaces and the corresponding on-screen keyboards are good enough for short texts but even writing a medium-sized email is a pain in the bottom compared to the full-size keyboards computers come with. Autocorrection systems make it less painful, but they're absolutely useless when writing formal languages like code or math and since their capabilities are limited, natural language writing isn't as easy as with a hardware keyboard either.
There's a reason for the name of the category "consumer electronics". They're meant to be good at consuming media, not producing it, that's what the workstation is for.