The idea that we are vessels for memes unacceptably undermines the popular understanding of free will and autonomy.
The idea of free will is incompatible with meme hosts and that makes the adoption harder, hence the fear of considering this perspective.
This is a sense of attachment to one idea, in favor of another.
Free will and Freedom can be seen as vaccimes for The Meta-Meme, due to the incompatibility of the two.
Whichever meme has installed first inside the host, is usually the one to prevail (similarly how children born in religious families have a high chance of sharing the religion of their parents)