I think it depends on the person and the requirements. I've written tens of thousands of words on an iPad, used it to do programming exercises for job interviews using Pythonista as well as prototyping bits of work projects and hobby programming, created character sheets for a homegrown tabletop RPG, filled out PDF forms, my kids draw and paint on their minis as well as write fan fiction in Wattpad.

There certainly are limitations due to the form factor and Apple's lockdown of the platform. Pythonista and other dev environments would be a lot more useful with less strict code sharing options. Still, you can do a lot with these things.

Maybe it's because I don't own a laptop, carry the iPad frequently and use it on my daily commute.