When I need to write something, and I have a computer, and something is inconvenient, I can quickly (well, within minutes, maybe 30 of them) alter it to my liking, and return to writing.

When I only have a pen and paper (which I used extensively for writing at school), many things may be inconvenient, but there's no way to fix it. This may turn into a source of a low-key stress, and interfere with my writing much more than tweaking a computer would.

I use Emacs, an ultimate tweaker's tool, for writing every day. Last time I had to tweak something in it was a few weeks ago, and it took maybe 2-3 minutes. It's a small price to pay for a tool that just does what you need, when you need it, with zero mental load, and zero frustration.

Pen and paper for writing. Computer for editing.

how did you decide which pens to go with?