I’ve been using this for years.

#1 it adds a new layer of security if there is a breach and you use a different, but not obvious, tag for websites like me+amazon@starfleet.org, me+netflix@starfleet.org.

#2 it helps to know if a website you sign up for sells your information, so if you get penis enhancing product ads sent to me+FreeOnlineGamez@starfleet.org then you know where it came from

#3 some sites don’t allow the + so you’re screwed