Your title says it all--they take themselves too seriously. Some of the publication guidelines are insane, and the tone, so righteous and preachy. It must be intentional, because they're writers, and writers know how to modulate tone, you'd think. I'm looking for people who are excited by creativity, have some flexibility and humility, and don't think their publication and their ideas are sacred. Important, yes, and high standards are there to be met, but some of it is too much. You know it wasn't that long ago that medium.com didn't have any publications at all.