It appears to me that a lot of the threads that endure past two pages—especially the "how-to" and advocacy varieties—often lead to conflicting opinion, and some to outright acrimony.
I realize that diverse opinions are the lifeblood of any lively discussion, but offerings like "I got run off the road by a car" almost invariably evoke at least one response suggesting it was the writer's fault.
Offerings like "I got run off the road by a car while wearing headphones" invariably bring out the "What have headphones got to do with it?" crowd.
Some one who posts "Since I got run off the road by a car while wearing headphones, my headphones are now full of gravel. What's the best way to clean them?" soon initiates a clash of opinion as to the proper methods, with people quoting sources, and trashing others' sources as obsolete and elitist. Some maintain, of course, that the writer deserves to have headphones full of gravel.
I guess I expected more commonality. So far the only universal opinion seems to be "Bicycle thieves should get life in front of a firing squad, and I should get to kick them."