@uncrtn Text selection. Text selection. Text selection.
The functionality and ergonomics of text selection in iOS are absolutely horrible when using an external keyboard. That's my primary beef. All of the arguments Apple makes against adding touchscreens to Mac? Yeah, those apply equally against using an iPad with an external keyboard. Except with an iPad you can't use an external trackpad or mouse.
And writing for a lot of people requires the use of a ton of research, notes and references. That generally means a lot of browser tabs and quick switching between the browser and the writing app, esp. when you're writing longer texts.
Which is very awkward given the constraints in iOS and hard to fix because there are fundamental limitations to how useful non-touch external screens can be in a touch-only OS.
You're also let down by iOS Safari, which just isn't in the same class as the desktop version. And it doesn't really matter how good the competitors are because you can't change the default browser.
If you're working with images, you also need to easily switch to and from a graphics app, which gets very clunky very quickly in iOS if you're making iterative changes to the graphics (edit text, update image, edit text, update image, etc.).
Finally, even on a desktop it's really easy for me to come up against the limitations of an 8gb laptop just because of the browser tabs I have open and are relevant to my current task.
The 4-6gb the current iPads Pro come with is barely enough.
For a lot of people, involved writing tasks on the iPad are just horribly, horribly awkward and most of it (except the RAM issue) is down to intentional iOS limitations.