So, a frequent distinction made in the polyamory community is between descriptive and prescriptive hierarchy. I guess I find this distinction to be very confusing. For instance, I just read somebody in another thread say they did not practice prescriptive hierarchy, and yet they also said they build long term commitments with some of their partners. And I see this a lot, people say they're descriptive but also say (or strongly imply) that they are committed in various ways to their descriptive primary.

This confuses me. If you are committed to somebody, you are saying you intend to have a certain type of relationship with them now and in the future, and you will work to maintain that relationship. How is that not prescriptive?

Here are some made-up examples to illustrate why I'm confused, are these couples prescriptively hierarchical or descriptively hierarchical (because I don't know)?

(A) Bob lives with Jane and they have been in a relationship for 5 years. Neither Bob nor Jane wants to live with other people, so they aren't open to living with any new partners, and while they don't limit how emotionally close they might get to other partners, living together means they will always have a certain intimacy that they don't have with other partners.

(B) Gary has been in a relationship with John for 8 years, and they have a very uniquely deep connection that they don't feel with other people, and they spend a lot of time together as a result. They value this dynamic highly. They don't have veto power or many rules, and they can get close to their other partners. But, they also know they would no longer be happy in their relationship if one of them became as close or closer to another partner because (for reasons of time, emotionally energy, practical commitments, intangibles, etc.) their dynamic would fundamentally shift, and that would be too painful and they'd likely break up. Thus, they organically desires to put more time and effort to maintaining their closeness than they do with other relationships.

(C) Susan and Liz live together, have a dog and a kid together, and rely on each other as their "partner in crime" in many facets of life. Over their 18 years together, they have become so enmeshed and important to one another that the thought of breaking up or radically changing their dynamic is unthinkable. They also find it impossible to imagine how they could ever be as enmeshed and close with any other, newer partners. Due to this interdependence and its importance, they commit to work to maintain their relationship even in the face of temporary difficulties in the relationship, even if in the moment other non-primary relationships feel easier.

Anyway, to a certain extent I feel like the community uses "prescriptive" and "descriptive" inconsistently, with the former basically meaning "hierarchies I don't like" and the latter meaning "hierarchies I do like". Maybe I'm just not getting it, but I've been reading about this distinction and have come away feeling more confused than when I started.

(Edit: And to be clear, I don't consider hierarchy to be intrinsically unethical)