Singletnormativity and "hostnormativity" (how we've been referring to beliefs that prioritizes the host over all others in their system, often with mistreatment and dehumanizing of the other members) is indeed a massive issue in the plural community, and we refuse to shut up about it because it's so prelevant that it's now frankly alienating us from the community.
The best way to deal with it is to be frank and discuss the issues as a community. So, here is my list of what these two issues may look like:
Expecting a plural to have a central/main identity and/or a host
Treating introjects like they exist as free entertainment for the host or others instead of actual people
Forcing the persecutor label onto members for simply disagreeing with others, or acts such as shittalking them, especially in public spaces, and generally being assholes towards members you deem "persecutors"
In general, being weird towards introjects, treating introjects like they're "blorbos in someone's head", and dehumanizing them
Treating one member of the system as the most important or real member of the system
Expecting members to have set roles, for them to have set purposes for existing
Sharing information, especially sensitive or private information, on other members without their permission
Pretty much only referring to a system collectively, instead of referring to members individually
Obviously, some of these things may not always be bad. Some systems prefer to be referred to collectively, some introjects enjoy being treated like fictional characters. That is completely okay when it is their choice! That's the important thing, letting people decide how they want to be treated and referred to and respecting those choices. But I have witnessed all these things happen to myself and other plurals, who do not want it, several times over the years.
It is a persistent issue in a community that is supposively about being more than one, and it only seems to get worse and worse. I hope that we can all have more discussions on this and work towards a communitity that truly treats system members as people, that respects their automony, and allows them to be themselves without mistreatment - Quinns (any pronouns)