(1) Dim-witted person tweets, or is reported to have said, something dim-witted.
(2) Equally dim-witted people notice and tweet their outrage.
(3) After a while, brighter people note the kerfuffle and decide to weigh in, either to reinforce or to critique the outrage.
(4) These brighter people are followed by even brighter people, who begin to see the whole thing as Significant and therefore requiring their response. They tweet and blog their thoughts.
(5) Result: the intellectual agenda of some of the brightest people on Twitter is, often for several days, established and directed by some of the most dim-witted ones.