Why are the Puranas mentioned separately from Smriti in the verse “shrutismritipuranadi..”?

The Puranic literature belong to the category of scriptures that are called smriti. Then why does the below verse refer to them as different from smriti?

shruti-smriti-puranadi-

pancaratra-vidhim vina

aikantiki harer bhaktir

utpatayaiva kalpate

“Devotional service of the Lord that ignores the authorized Vedic literatures like the Upanishads, Puranas and Narada-pancaratra is simply an unnecessary disturbance in society.”