The problem with “correct” pronouns is that what’s considered correct will differ depending on who’s saying it. There’s no confusion with “preferred” pronouns. Also, it is a preference, because some people use pronouns that are not the standard he/she/they ones. It’s not their gender that they chose, it’s (potentially) what pronouns they want to use to refer to said gender.
The problem with “correct” pronouns is that what’s considered correct will differ depending on who’s saying it. There’s no confusion with “preferred” pronouns. Also, it is a preference, because some people use pronouns that are not the standard he/she/they ones. It’s not their gender that they chose, it’s (potentially) what pronouns they want to use to refer to said gender.