You seem to have confused "my desktop needs" for "typical desktop needs".
And decent only starts on the far other side of that spectrum.
In my experience my iPad means I am using my laptop a lot less, but it's taking me more time to do the same things I did on the laptop on my iPad.
My current laptop has a 13 inch screen and roughly the dimensions of an 11 inch macbook air. There are very few times I find it less convenient than a 7 inch tablet, and almost none compared to a full-sized tablet.
The number of times I needed to touch the screen or switch apps made it a pretty inefficient experience.
If I wanted a 'cheap' device to write on again I'd probably try a Chromebook
If the form factor is uncomfortable, sometimes you can't program around a solution.