As a casual user, can someone explain the implications for me? They seem to have my username and phone number combo; can they use these for nefarious purposes?
That's kind of the thing about privacy. It's kind of slipping away, but if you don't care that it is then it's prob cause it doesn't matter to you yet.
Because if I do have an alias, which is doing very shady things. I would make it pretty sure, it's not going to be that easy to get it. When doing stuff like that you want to be sure that there's "shared nothing" approach. So if they hack your systems, your primary system won't contain any information referring to the shady side and vise versa.
We are talking about teenagers sending pictures to each other, not weed dealers in a prohibition state.