It's hard to grow an audience when you're literally years into a complex plot. Multi-year-long TV shows, and series of novels, have similar problems, but people expect depth in those media. The audience for comics is, I guess, less tolerant of a storyline that you can't easily enter without learning the whole backstory. It's sort of odd, too, considering that graphic novels / comics are considerably less time consuming than either of those other media. (I read the entire four-book run of Nausicaa, sitting in the passenger seat on the drive up to Ashland, a few years back.)
If you like comics at all, Goats is one of the strangest, and best. It's even available in the convenient dead tree format, that lets you read large amounts at one sitting, while riding the train. I need to get other people to read it and buy the books, because otherwise it will go away without getting properly finished. And then I will be sad.