Thats exactly what I was thinking - the main goal is to boost the main site, but those blogs are each standalone entities and sometimes even hide behind an avatar with a brand with social properties. So i though maybe to create some kind of an holistic system.If those content is legit (not spun content), then there's no harm monetizing those anyways, since they are good content.
I would create a 2-in-1 type of strategy, which the PBN is used to boost the primary website, but it also acts like a funnel to convert sales in the process.