When I was in college I got an early invite to Gmail, and did the fistname.lastname address.
All my day jobs have also had the same format, as does my university faculty ID (I teach night classes).
It’s kinda handy that you just use my (unique) name and the organization to get in touch with me.
Though it’s super annoying on my phone’s autocomplete since the screen above the keyboard shows “firstname.lastname@…” 3 times and I don’t know which is which.