In the 1990s, my high school and college gave me email addresses with an underscore between my first and last names. When I opened a Gmail account in 2005, I used a period instead — I don't remember why, maybe because I thought it was easier to type — and in any case, Gmail ignores the period and doesn't care if you write my name as tuckerlieberman@. On all my social platforms, I use tuckerlieberman with no punctuation, which has happily avoided the problem of "What if a new social platform doesn't allow that punctuation mark?"