There used to be a reason to have a 5.1 surround system, because that's how the movies were supposed to be enjoyed. There used to be a reason to engineer your home "soundstage" because that's how the music was mixed and optimally appreciated.
I don't think the bar of entry being money is truly the reason, rather that people have become much more passive consumers of media, and the producers have recognized that and absolutely enshittified their products.
As for the cheap speakers = cinematic experience, watch Interstellar with 5.1, then with the soundbar and tell me how equal the experience is.