The Tur lists a bunch of things you can't do on YT, like dance and clap or get married. He also includes, ve'ein machrimin מחרימין (think Kol Nidrei).
But who does that anymore? Are we even allowed to consecrate objects to kohanim today? Why include that?

Perhaps because in theory you still can, its just that practically speaking everyone is "impure".

(btw did you not ask a similar thing question here (where this is actually discussed at greater length)