@ChloeCat well. i know like at least 3 other plural systems irl among my friends (and ex-friends, long story) but i don't think any of them ever really mention it irl but they do online or when they found out im plural as well
so i think it probably is mainly about stigma and (lack of) safe spaces. we certainly dont give any indication of plurality irl unless it's 100% safe and there arent any strangers there etc etc. but then it's quite personal for us anyway so
sorry for rambling a bit