In my more sarcastic moments — of which there are many, oh so many — I muse that "What do you expect when you try to make a lasting advocacy organization out of poorly-socialized members of a fringe group whose reason for organization is mistreatment by moneyed or otherwise powerful outside interests?" In an excess of candor and introspection, I sometimes admit that describes me (at least at times), too.
And, of course, the problem then comes from defining "nice." For some people, "nice" means "worship my past accomplishments — no, don't examine them too closely, just worship them — and then transfer that worship onto me, and fan me with tropical leaves while I bask in the glory of all this worship, and ignore the blood on the hem of my toga (it's not from anyone you know anyway)" — and that anything less than that is not nice. For other people, "nice" means "respect that I'm different; worship my difference, because it makes me superior to you." For still other people, "nice" means "gimme gimme gimme." For yet still others, "nice" means "let me be one of the kewl kidz right now, because I really can be one of the kewl kidz, I'm just as good as them." And so on. Sometimes they're all "right"... and I can name one individual who fits all of those descriptions, which proved to be too much when that individual acted on them in rather inimical ways and got expelled from the organization. As another example, if you're going to be a Sherlockian high-functioning sociopath, you'd bloody well better be as brilliant as Sherlock — not just believe that you are, but be that brilliant, with a virtually unblemished record of accomplishment, and no mistresses/gigolos/second families on the side while your (arguably more-talented) spouse has been forced to retire due to a debilitating illness without ever admitting that anything was even slightly questionable. Mere aspiration to godhood isn't enough.
I am not going to lament "Why can't we all just get along?" because we can't. We're bloody humans (even in the arts), and we don't do that kind of thing, or at least not well and consistently. Sharing one interest doesn't ever mean we share any others — just look at the set {Ezra Pound, Robert Frost, Natalia Gorbanevskaia} — and the means of achieving shared ends matter. Indeed, part of the problem is that organizations in the arts can't even agree whether their objectives are ends or merely means to other ends...