You might put "they/them" next to your name if you prefer not to be referred to by a gendered pronoun.
Not putting pronouns next to my name, doesn't mean I don't want to be referred by a gendered pronoun. I'm pretty sure people can guess correctly my gender.
That's fine, too. I typically don't specify a pronoun. Call me what you like.
My point is that this is not the case for everybody. Some people prefer not to be called "she" even though I might guess that they're a woman.
Can also be helpful for names that are commonly male or female. Or foreign names. But there's not really a need to list multiple pronouns like "they/them/theirs", is there? Doesn't "they" say it all?
Only would make sense when it's "she/they" or similar. Otherwise it's just redundant.