'Uncommitted delegates' on 2024 primary ballot

I just received my ballot for the Washington primary and there is an option to vote for 'Uncommitted delegates'.

[link:https://pcdn.columbian.com/wp-content/uploads/2024/01/Sample-Ballot-March-12-2024-Presidential-Primary.pdf|

Voting material says 'A vote for "Uncommitted Delegates" allows uncommitted party delegates who represent Washington to decide during their national convention'.

I've never seen that before, but this is my first WA primary. I get how it works, but my question is why is that on the ballot?