Different masks for different situations/groups. Yep, that is a thing. Work vs not-work. Friends vs strangers.
As to anonymous, I think if I wanted to remain anonymous I shouldn't have posted a picture of myself every week for a year. 🙂 I'm not posting my address and phone number though so I think it is a bit of both. The parts that need to be anonymous are, and the rest is fine to show.
I agree with you completely, on all counts. Sure, security is an issue and it would be stupid to put too much out there, but there's certainly merit in opening up a little. Of course, it's dependant on many factors. I'm sure there's people who wouldn't want to plaster pictures of themselves everywhere, cops for instance...Although it happens all over Facebook and Instagram right? Personal choice.