When I explain it to my non tech friends, you can use PC to "consume stuff" or "create stuff".
So you can watch, read, liste to content someone else created.
That takes care of all Youtube, newspapers, books, any content you browse trough. Here all you have to do is to navigate, start and stop and such. Also you can read your e-mails, facebook or such, and occasionally write some response. Mind you, response won't be long, will be in bastardized shorthand (that people invented because it was awkward to type) most of the time with no proper punctuation and grammar. But sometimes you just need to know that your sales rep sent you the quote, you might even open it and check numbers quickly. And then respond with :" Thanks Brian, I ll talk 2 you tomorrow..."
If that is what you use your computer for 90% of the time, yeah, you'll be able to do that on a tablet. Or a phone to that matter. Because you only "consume stuff" and that can be done with dumbed down interface of tablet like devices.
Everything else, where you actually have to answer with a coherent text, that has more than few sentences, that have some kind of formating, where you actually create content of any substance beyond instagramming or "thanks I ll call you tomorrow when I get to office" you cannot do on tablets. Screens are cretinously small, you have no normal keyboard on which you can type with 10 fingers and have keyboard shortcuts, and your pointing device has a resolution and accuracy of points of the compass (" he went North, officer", said he pointing finger towards the mountains..).
Even proper E-mail response is much easier on a propper PC. Creating any kind of report, editing photos, writing documentation, programming, doing any kind of CAD, circuit simulation, etc. etc...
It is as simple as that. The fact that some people, at great effort, are occasionally doing something a bit more complicated on tablet platforms, is a testament of how misguided they are, not that it it's a smart to do..