FYI means "for your information". We use it when we are telling people about settled facts. It's also three letters that based on context could be seen as condescending on their own.

When we are discussing not-settled facts, there's better ways to frame our discussion.

For instance: "I believe, that CDM is an antiquated theory and MOND is a better explanation, because _______. I've had discussions with ______ and in particular ______"

It's less effort than your opening flame, it's less abrasive, and it opens productive discourse. Your opening statement is more like that of a political partisan than someone seeking discussion.

Intelligent and good people have followed the advice above, and the result has been more error and harm.

Therefore, learning from their experience, the one thing that works is accurately calling the status quo's invisible blobs of noninteracting kludge as what it is.