What is particular about Psalms according to Exclusive Psalmodists?

I've run into some adherents of [Exclusive Psalmody](https://en.wikipedia.org/wiki/Exclusive_psalmody) in my denomination. The general argument they've been running with is that if we teach the inspiration and perfection of the Psalms then they should be sufficient for the Church. But if that's the case, then why are they okay with all of these church service components when they also have perfect Biblical instances: - prayers (numerous) - creeds (for example 1 Corinthians 15:3-8, or Colossians 1:15-20) - sermons (Jesus' many sermons in the Gospels, the Apostles' sermons in Acts, or I've even heard Hebrews described as a collection of sermons) If writing new Psalms is opposed because the Biblical Psalms suffice, then what is distinctive about the Psalms that the same argument can't be applied to these other forms? Shouldn't the sermons of the Bible also suffice, to be read aloud but not expounded upon? Shouldn't the many prayers of the Bible suffice? Exclusive Psalmodists would presumably say no, that there is a place for Christian teachers/ministers/pastors to write new sermons and prayers etc, and that it's appropriate to recite the creeds of the Church. (I've never heard of any church which forbids all new works and allows nothing but reciting texts of the Bible!) So, according to Exclusive Psalmodists, what is particular about songs that is different, that means that the teacher can pray something not taken directly from the scriptures, that they can write and deliver a prose sermon, but cannot write and lead the congregation to sing a new song? (I've tried asking this question to the exclusive Psalmodists in my denomination but haven't gotten an answer yet, so thought I'd ask here in case anyone has a good explanation.)