It wasn't so long ago that the world of blogging was very new, and many involved were testing their chops by being puritanical about other people's behavior.
The role people took on was known as the Curmudgeon, it was easy to be a curmudgeon; all you had to do was find a principle and rail against someone for overstepping the line. No time was spent in constructive criticism or god forbid dialogue. Rather than stop, count to ten, and try to see the other person’s perspective or ask if that’s what the other person meant the curmudgeon found it easier just to make personal attacks.
Curmudgeons were rewarded with traffic, notoriety and successful IPOs.
Once curmudgeons had something, they became part of the establishment; the curmudgeon toned down their rhetoric and spent less time criticizing other people and more time trying to maintain their existing relationships.
As new social networks rose, new curmudgeons appeared, though we haven't seen any curmudgeons on Foursquare, yet!
If you are a reformed curmudgeon or think you might be suffering from the disease, I wrote a post about measuring your level of curmudgeonliness called the curmudgeon meter which was followed by, “How Should You Criticize People On Your Blog?” Check out the meter and compare your level of curmudgeonliness.