It seems hardly new to me that you generally don't hug or pat strangers, or colleagues you haven't established good terms with (yet). If people engage less in s

It seems hardly new to me that you generally don't hug or pat strangers, or colleagues you haven't established good terms with (yet). If people engage less in social grooming (-ish/like) behaviours, then this most likely is caused by (1) smaller social circles and/or (2) social interaction being handled through "social media", not in-person. Behaviours in the "social grooming" category are extremely important for humans, even though we, as a species, developed language specifically to reduce the need for it in maintaining relationships in larger group sizes. This fact is reflected in these behaviours being reserved for relationships of at least some intimacy; proportional to the behaviour in question (e.g. hug -> friend, snuggling -> SO). Worth pointing out that some have been professionalized for a while now (like getting a haircut).