Then that's ok, but just because you don't see value, interest or anything at all, doesn't mean that other people's passions are wrong, or that they are less than you who create original content.
I don't take part of that fandom, so I won't know the details. Same applies to fans, just because they are fans doesn't mean everyone is aware, or simply don't share your same anger. People can create content, demonstrate their abilities, getting themselves to know just based on what they enjoy, some don't go as far as to know the lives of the actors, the company projects, what other products or merch they create, some don't even care about a movie or season. Some are not aware of these things for their entire lives too. Just keeping it basic and enjoying the media
If that's how you see it then ok, but there is more than plain """extreme""" consumerism, a lot of people don't care about premium items, every piece of merch or whatever. Some may have the main source as an atlas but they want to see other type of content they know don't have in it, what ifs, different scenarios, new creative ways to see a character in a specific situation, or simply an exhibition of skills.
Well, the same could be said about your hobbies, talents or passions. they could totally see what you do as a waste of time, as something meaningless too. And there is nothing wrong with granting more meaning by creating something, or investing themselves on that, anyone would say "Oh you're so talented" and then check out what else the creative can make, what other projects they have, etc. Companies are not the only ones getting advertisement.
You're free to not make fancontent at all, interacting with fandoms is only an alternative for when you want get at least a bit of engagement quickly and it mostly works when it's about something you're passionate about but if you're not passionate then just doing it because that'll be quick engagement will burn you out rather quickly, doing trendy stuff is not an exclusive thing of tumblr, it has been a suggestion either for growing an account in SM, getting commissions or similar.
There are artists who exclusively make original content, you can try to be one, making sure that your work is deep, interesting enough, maybe you'll find something according to your standard and values, and give them the appreciation that under your personal consideration you think they deserve, then by doing that you're no different from a fan from another franchise, seems that the only difference would be that under your sense of superiority as an original content creator, you for some reason are in the right while others are in the wrong.
Hope you can make a successful blog, but that your supporters don't have much fan attitude towards it, as I believe you dislike that behavior.