So it's that time of year again. The time of year I start to see people wearing lightweight longsleeve shirts with North Face vests over them instead of wearing coats. Why is this a thing? Are there people out there whose arms don't get cold?

I tend to associate this with harcore levels of prep, a sort of Stuff White People Like phenomenon. But I'm white and I don't get the point of winter vests. Whose idea was it to chop the arms off a coat and call it reasonable outerwear?