Probably for the same reason that most people don't use caps when typing. You can do it but most people won't have much respect for you if you do.
Welcome to the forum.
Your intelligence is surpassed only by your ignorance.
You are more likely to fall down the stairs and break your neck if you live in a house with stairs. You are more likely to be in a car accident if you drive to work. You are more likely to be kicked in the nuts or punched in the nose if you practicing the martial arts. - Judge Pen