Free-floating beliefs have to at least feel like beliefs. You can't even think you have a belief about whether Wulky Wilkinsen is a barnbeanbaggle unless you think you have some idea of what "barnbeanbaggle" is being used to mean. The thing about using a made-up word is that it's too easy to notice that you don't know what to anticipate from it. The thing about "post-utopian" is that, even if you have some idea of what "post-utopian" is supposed to mean, being told (by someone you perceive as sufficiently authoritative) that a certain author is "post-utopian" is quite likely to just make you selectively interpret that author's works to fit that schema. Similar to how you can make professional wine tasters describe a white wine the way they usually describe red wines by dying it red.