The traditional crafts of knitting and crocheting have in recent years made a big comeback. In the age of digital detox, knitting and crocheting reduce stress and, according to some studies, may even go a long way toward preventing memory loss. But while there’s much to be said for the calming effects of grabbing yarn and needles and getting to work on a sweater, an equally important part of this centuries-old tradition is its ability to bring people together.