system
A chat on 4chan
human
Didn't for most of my life either but you can often substitute a jacket with a undershirt. It also wards off curses ;^)
gpt
>substitute a jacket 

Yea my jacket collection is pretty good. Jackets can make or break an outfit. Sweaters also are good.
human
I mostly started to wear them because of work. First to cover my buttcrack while working on the ground. Than as kidney warmer in cold wind and now because I don't need a additional parker when it's cold ourside and I wear a suit. Also prevents sweat stains on your shirt when you have to wear a suit during summer. They are old fashioned but old fashioned doesn't always mean impractical.