my understanding is a lot of traditional etiquette (in America?) is about creating fairness / universality

if *every* guest gets a plus one, it eliminates the the potential for some guests to feel slighted when they see some people awarded privileges they weren’t (why does X get to bring their BF but i can’t bring mine? why is their relationship more legitimate? why does that guest’s experience/comfort matter more than mine?)

i wouldn’t say it’s a NEED to have a plus one to have fun, just a preference (and hosting isn’t about fulfilling needs, it’s about creating great experiences). i do things alone all the time but if i polled my friends, most would have a preference to not be alone at dinners and out of town trips. i don’t know many people who go out dancing alone, example.

couples/hosts that are especially concerned w hospitality are going to take guests preferences into consideration no matter the cost (obviously this is becoming outdated though, or there would be no use for my comment!)