Most creators work incredibly hard to make their works accessible to their target audience. They try to make their works as interesting as possible, to ensure that their audience remains engaged throughout their experience. Part of this is commercial; after all, many works are created with the intent of making lots of money. But it's also about wanting to make your audience happy, and about being able to share one's work with others... which is difficult when people don't want to read/listen/watch/play your work.
But some artists are believed by their critics to consider a work's inaccessibility to be a badge of honor. They consider the boredom of general audiences to be a sign of their artistic integrity, since most people only like soulless tripe, anyway. The result is this trope, where a work is considered to be artistic specifically because it is painful to slog through. Every dull, agonizing second is an affirmation of a work's artistic integrity, because why would anyone watch it otherwise? Conversely, some may claim that a particular work isn't artistic because people actually enjoy watching it. True Art, after all, should be respected in its own right and on its own merits, not because people enjoy it.