"Complaining" aside, boards like these also thrive on controversy and conflict. Factions even form, and groups sharing like views start to kinda "collectively" fight the opposition.
Take a simple issue, Sloan as coach, for example. The opinions about Sloan's methods, effectiveness, and desirability as a coach run the entire gamut. Many are generally satisfied with Sloan, while having some complaints about him or his "style." Others are dissatisfied, but don't actively try to advocate that he should be fired, or otherwise make repeated attempts to attack his faults, as they see them. Those people are kinda "in the middle" and it's not an issue that concerns them much, really.
Others are not "in the middle" and have very strong opinions that Sloan either is, or is not, a good coach for the Jazz. The "extremists" tend to be more committed to their views and more likely to espouse and articulate their opinion on the matter. In is in fact the "extremists" who generally propel the continuation of most threads. Without them, a few mild opinions would be expressed, and then the thread would quickly die.
Many who are NOT extremists (as I have labelled them) are nonetheless entertained by the spectacle of the extremists on both sides doing "battle." For them, it makes the board more "interesting," even if they don't care to personally get involved in debating the conflicting opinions.
At the very extremes, you find those who get those who display a pronounced "hatred" for their opponents. They come to "hate" a person or persons merely because he/they support(s) (or do/ does not support) Sloan, for example. Very often I have seen their "hate" turn into little more than incessant personal attacks on those who disagree with them. Again, for the average message board poster, this merely adds to the overall entertainment value of the board.
Some of those tend to "favor" one view, or another, but who don't care to "debate" it, find expression in acting as a "cheerleader." They often come into a thread without knowing, or even in the least bit caring, what the thread is about. They don't even care to know what the purported "discussion" is about. They are simply there to support their favorite "team" whatever the topic is. In order to do so, they frequently jump in with a post that, in effect, just says: "You're right, homey! You tell him!," and nothing more. Once again, it keeps them interested, and gives them a chance to "participate," even if they don't care to discuss anything.