Why do some social apps don't allow periods or underscores in usernames?
Twitter doesn't allow periods in the username; same with Telegram. Gmail treats email addresses with periods and no periods as the same, but doesn't allow underscores. Instagram and TikTok allows a mix of periods and underscores in their usernames. Is it simply a matter of choice by the creators or there's some technological or design-focused reason behind why social apps don't allow either periods or underscores in usernames?
👤 slater Accepted Answer ✓
XSS or local execution stuff
think about it, if you ran a social network, you wouldn't allow usernames like "../system/pwd/" (dumb example, but you get the point)