Young millennial male, every single person I know uses Venmo. IMO this article largely misses the point of the app. It's replaced cash/checks is all, it's not some huge social upheaval in the way we use money that needs to be analyzed. In my experience it's rarely used for splitting bills for dinner or picking up bar tabs (I can't remember the last time I went somewhere that wasn't able to split the bill on their end…
For our generation, this pettiness goes the other way, too. I will literally try to buy lunch/coffee/dinner for someone, and after I've gone home, they've sent an unsolicited 'repayment' to me by Venmo. And on the other hand, it's difficult to "split your case of beer" with someone -- people are afraid to partake because they're worried you'll bill them afterwards, and they can't afford the $3 in this month's budget.
Also, beer example was just meant to highlight that friend we all have who practices "selective accounting" with our informal running tab. If I had any suspicion that $3 is make or break to someone I would gladly pay them what's owed and forget about the beer. Beer (and all vices really) have their own set of norms.