Writing is formally setting aside the time to complete all the thoughts that we all have, and may even complete inside our heads. Can you know you understand or really don't understand something until you express it? It is a luxury in the way any developed skill is. A gymnast who shows what the body we are all given is capable of, a carpenter who with universal spatial skills can build something that any of us could if we devoted the years to the rough shape and fine nuance of skills. It is an indulgence to do what you must instead of living in as much compromise as possible.