A typewriter enforces a discipline that no word processor can replicate. Each keystroke is permanent, each line irreversible. You think before you type, or you waste paper. This constraint, which seems like a limitation, is actually a gift — it forces clarity before expression.
The mechanical linkage between finger and letter is satisfying in a way that pressing a membrane key will never be. You feel the resistance of the type bar, hear the clack of metal on ribbon on paper. The machine is not hiding anything from you. Every part of the process is visible, audible, tactile.
I keep a 1962 Olivetti Lettera 32 on my writing desk. It is slower than my computer by every measure, and better for thinking by every measure that matters.