When a barrier to entry is high, fewer people attempt to enter or succeed at entry. Consider blogging. If a person feels that their analysis is important, or that stating their view point would reflect upon them, the barrier to entry is set high. When anyone feels that they can voice their opinion, and they don't have a high opinion of themselves, or respect for others, they post all sorts of time-wasting, or perhaps profane drivel. This is what we see when we look at Twitter. Anyone feels like they can enter, and those who do sometimes just have nothing but time and a desire to self-aggrandize.