I've been writing decades longer than I've had a computer. It's a matter of routine. Besides, my computer doesn't run all day, while I can write in a notebook any time I want. Plus, I can make the first corrections while typing up the stuff already-

Although, if I want to be perfectly honest, the true reason is that nothing I don't have in my hands as hard evidence does seem real to me. So, the cabinet in the study is full of notebooks, with literally millions of hand-written words in them.