It is a cultural/generational thing. Millenials don't think twice about this. They are shocked that anyone would care. Non-millennials are shocked that anyone would share their financials publicly. We're all shocked at each other's behavior.
There is a long list of people that I know that don't use Venmo because of the "social" crap. Please don't try to brush this as a "millennials don't care".
I think by Millenials he really meant to say Gen Z.
"Millenials" has become a catch-all term for "young people" over the past 10 years, but the reality is that we are no longer the youngest generation. Older folks just haven't caught up to that fact yet. Anyone below age 25 now is a completely different generation from us. "Getting" Snapchat and Venmo seems to be the dividing line.