>>281513023
It used to be. Consider that for some people who had to travel, or lived far enough apart, not being able to see someone, perhaps ever again, was entirely possible. Even compared to twenty years ago, now you can just videochat with people almost whenever. But a hundred years ago, someone might be in a few towns over and it'd take a whole day trip just to spend any time near them. Letters could take time to reach people. You could go days wondering what someone was up to and not be able find out.
And hundreds of years before that, it was even worse. Travel even slower, letters taking forever to get anywhere, if they got there at all. In that sort of environment, you had a lot more worth placed on personal symbolic gifts. Hair is both very personal and easily cut and replaced, among the young, so it's an obvious thing to give someone to be a piece of them to hang on to.