Absolute Brahman resembles One possibility of Perfection, not all possible Perfections, i.e: He is surely Perfect, but resembles One mode (model) of Perfection.
Absolute Brahman is One.
The Creations (Jivas) are the Many.
There are some Jivas identical to Brahman, but not all Jivas.
Some Jivas are perfect, some aren't but able to be perfected, i.e: integral.
Why we supposed that Brahman is the most perfect entity?, Doesn't He represent only one mode of Perfection?
For me, some Atmans may be of more Perfection than the mode of Brahman.
So, for Shaiva, why they supposed that Shiva is Brahman. And Vaishnava supposed that Vishnu is Brahman?
Why not Shiva is the most Perfect mode of Perfection, but he is not Brahman?, Why not Vishnu is the most perfect mode of Perfection but he is not Brahman?
It is clear that Brahma is the personified Brahman, and this resembles one mode of Perfection.