It might be a case of trying to compare 1:1 type of building? Or perhaps full hellhounds conversion and skill investment is too expensive compared to an ammy slot pet.
This player did cold pets around 6 min CR with a 2x Winter King itemization.
Although it says hybrid, it is basically full pets with similar RR. Both your and this build don’t have birds, so the main difference is the hellhound skill investment and itemization - and a different method to proc extra pets - as well as fairly substantial Wendigo Totem investment. I’m not sure how much the acid pet damage contributes.
It is less piano by a couple of skills, I think.