I think for polycules it makes sense to have such practices, as a filter for people who don't want to contribute/share even something as simple as a subscription, and to make sure that they are on the same page with the membership of the other partners: if they don't agree with sharing the password, they might not be a good fit. People in polycules share partners, which is something so intimate, most people wouldn't be ready to do it (me included). It takes a lot of work and communication to maintain not just one relationship to one person, but multiple ones to multiple people. Paying for a subscription that you share with others is comparatively easy. And obviously, for existing members, having additional people means more subscription services you can watch.