The USENET news group rec.food.veg is famous for its flame wars. One favorite of mine was about whether vegans or omnivores were more subject to vitamin B-12 deficiencies. It got pretty ugly.
Flame wars can be amusing for the twisted among us to read. (I particularly enjoy reading the outrageous flames sent by readers complaining about the flame wars.) Nevertheless, it's generally considered rude to subject other readers in a discussion group to a protracted flame war, especially when it gets personal. Perhaps more important, prolonged participation in a flame war can get you a really bad reputation on a discussion group. Imagine losing the respect of hundreds -- even thousands -- of people you've never even met! If you want that kind of abuse, you might as well run for president; the pay is better if you win.
USENET participant Graham Wolff Christian points out that flame wars are almost ubiquitous. He writes
*Every* discussion list of which I have been a part--no matter what its subject--has fallen victim to such ills--a few have gone down in e-flames. The pattern is absolutely consistent. Writer A drops a light remark--always *tangential* to the main discussion. Writer B interprets the message in the worst possible light and fires off an outraged reply, in which writer A is called a racist, a classist, a fascist--whatever seems to apply. Writers C-L chime in, rather like the crowds in a DeMille film, muttering "Shame!" or "I agree!" or "A is right!" or "B is right!" Writer A replies saying, "Gosh, it was just a joke. I'm not a fascist. Lighten up." Writer B says, "This issue (the South, date rape, Nicaragua) is DEADLY SERIOUS. I won't lighten up. I won't." By the time things have cooled down, Writers A and B have left the list; or Writers N-DD have left the list; or the list has died. These are not *odd* occasions--they happen to *every list.*
In the worst-case scenario, a protracted flame war can destroy a discussion group. Inevitably, the least common denominator principle takes hold, and the group sinks to the level of the loudest and lowest flamers.