I don't find it confusing - but regardless of whether you find it confusing or not, you don't have to understand something in order to respect it.

If people want to be called they/them, it's because neither he/him nor she/her describe - either in part or in full - who they are; you don't have to understand that, you just have to recognise that their understanding of their own gender has led them to this form of presentation.

Also, they has been in singular use in English for centuries.

And Multiple Personality Disorder is outdated terminology - it's now classified as Dissociated Identity Disorder. And people with DID aren't a joke either - DID forms when the brain protects itself from repeated and devastating childhood trauma,.

Sorry - I feel like I'm always being 'that girl who corrects people,' but on the other hand, if no-one ever corrects mistakes, then they stay mistakes.