Define productivity then. It seems the critics all try to stack the deck by limiting productivity to stuff like excel or autocad which they know are easier to run on a desktop than a tablet. Which seems pretty disingenuous to me.
As a teacher, I don’t really do anything which requires a lot of specs, but mobility and ease of use do matter to me. My desktop can’t be used to annotate on pdf documents in notability, scan documents or take notes in a meeting. I have even edited a video in lumafusion and using the pencil feels more intimate and natural than a mouse. I get to share apps with my iPhone (and vice versa), and I like that my iOS devices are mirror images of each other.
My main two bugbears with my iPad at work is that the gmail app doesn’t allow me to natively attach files, and that Google docs still sucks (both the app and browser). But otherwise, everything else is great.
Sure, a Windows tablet equipped with stylus support could well perform the same tasks on paper, but the experience just isn’t the same. The app selection doesn’t seem as robust.
This in essence seems to herald back to the MAC vs PC debates all over again. People obsessing over specs and listing out what each device can do on paper, without realising that software makes all the difference in user experience. And for the work I do, I am now at a stage where I prefer iOS over macOS or windows.