It was John C Dvorak who picked up on the use of this term by bloggers. No issue too large or too small could fail to be adequately addressed by berating someone for not getting it.
It sounds like cult-like behavior, and in fact has a cult pedigree...
The giveaway that cult thinking is present in any environment is how responses are given from possible cult members to probable nonbelievers. If you disagree, then you "don't get it." Werner Erhard of EST (the über-cult of the 1970's) used to use this phrase over and over. Tell Erhard that something makes no sense. "You don't get it." Tell him that something is self-contradictory. "You don't get it." Tell him that something is just plain stupid. "You don't get it." This is the level of debate you can expect when cult thinking is present.
But, of course, "I don't get it."
Now you might think this would cause his opponents to change tack. Or at least rephrase the accusation.
Er, no. Four months later, came this devastating reposte...