Now this is an interesting discussion.
Sugar is fun. It's amazing on cakes and candies, but it can also create some pretty dangerous behaviors. Agendas and memes, in themselves, are not necessarily a problem. But, they can facilitate other behavior that can become toxic quite fast.
First, the agendas will create a distance between you and the story. The story will not be here to surprise you, but will be used as a tool to deliver your expectations. This, on a long period, can damage the way we read.
Then, there is the fact that agendas are parasocial behaviors. This means that when we attach ourselves to a character, we attach a part of ourselves on them and when said character is facing hardship it can be hard to see the situation clearly.
Lastly, agenda and meme are tools of conflict first. Meaning that an agenda only rise when there is a counter agenda against it. When a person is convinced of something but others are not, it creates a reactance that pushes us to keep up. And while it happens that we pretty much all agree on something, most agendas are the results of clan wars through the parasocial behaviors I talked about.
For these three reason, agendas can be dangerous, not only for the reading experience, but also when used socially. This is why I believe that it is important to promote not only agendas and memes, but also real positive behaviors.
If we don't do that: The balance will shift either toward toxicity (if agenda are the main things talked about in a social space) or toward gatekeeping positivity (if people are pushed to never criticize the material in a social space)
We must find the right balance. And the community will not only strive, but extend far beyond the simple material and fandom