People weren’t really walking around the house talking to themselves. I guess Siri existed but I don’t think (?) it was that popular.
Going to library → Google
Looking at photo albums → FB
International calls → Skype
Call a taxi → Uber
Not new behaviors, but newly popular.
Postal mail →
Email →
Group email →
Facebook thread
Try replicating a Facebook thread with postal mail! You’d spend a fortune in stamps. Imagine mass mailing every comment.