Yes there are many people that don't subscribe to the point of view that one partner is deserving of more love, time, energy and support over another. Some hierarchies exist and are declared valid due to children, shared assets, marriage etc. That can work for some but usually poly people discover that while they have these ties that bond, love is love and does not follow an agenda. Over time, most poly people grow out of the hierarchal system and theory and let love become abundant and ever growing. This can take time, patience and much experience. The experience comes from separating from couple-centric, co-dependent modalities and embracing committed autonomy with partners.
Try doing a tag search here for "hierarchy" "secondaries" "secondary" "primary" "primaries" and any other tag that seems to be relevant. I like that you are researching. Good for you!