I have a bizarre point to make.
Decades ago, I wrote and taught a high school computer science course. At the time, a computer was defined as having input, output, memory, and a CPU. By that old definition, smart phones, iPads, tablets, etc., are computers.
And by that definition, Chrome and Android, when combined, outnumber Windows devices. Somebody is getting scared, because persuasion isn't working.
There are lots of devices some would call toys, that others call a PC. Iot devices like the Raspberry Pi's etc for instance. My Pi can't do some of the things my PC can do but there are things I can do with my Pi that I can't do on my PC. It all depends on what your using that device for. PC to me, doesn't have the same meaning it did years ago.
Maybe it's time to drop the PC label altogether though I agree with your definition. Personal Device would be a better term, in that case Windows is not the dominant OS by any means.
Microsoft in my opinion by making Windows 10 effectively a device OS have opened themselves up to loosing even more overall market ground if you are going to have a do it all OS, then why not pick an alternative to Microsoft?
Windows10 is by far the ugliest Device OS out there people on the whole simply do not like it, just look at the miserable market share of the Windows phone.
As for a PC OS (desktop or large laptop device, which is still what most people mean when talking about a PC) then the same applies, Windows 10 is clearly meant for a tablet, then why not pick another OS ?
To me at least, a PC does much more than say an android or chrome book. With a PC you can create new programs in multiple languages and you can't do that with a Chrome book or an android device. Even with a Raspberry Pi you can write code and create some programs in Python.
So the term PC is still relevant today.
I prefer to call them devices. Microsoft, as far as I can tell, is leaning that way to. Lots of devices fit the description of a "PC", but to most, aren't really considered a PC. It's a grey area that just gives me a headache in my grey matter.
As far as 'PCs', that term was originally used to differentiate IBM and clones running DOS from other systems at the time, and after 84, you had PCs and Macs. Macs really weren't all that useful at first (The company I worked for at the time had one of the first models. also a Lisa with a HARD DRIVE OMG, and it was really a dog... but intriguing. Microsoft's efforts at a GUI were laughable for years). I think it's still useful to differentiate between desktop/laptop computers, tablets, and phones. The terms still have meaning, even though my desktop sits on the floor