I have a friend of a friend who's a tech executive at Facebook and mentioned in passing that there are like a couple dozen engineers that build the web ui. The rest (what like a zillion employees??) all develop the mobile app. (I'm being silly I understand backend and ops and all)

I'm not sure how to phrase this other than, there seems to be nearly no sympathy or tolerable path for people who don't want to use a smartphone. That was the largest shocker to me. I had no idea how large the transition to mobile was over the past 4 years.