It is a truth universally acknowledged that the one thing a composer hates above all else, more than war, oppression, racism, Hitler, the Daily Mail, music critics, anything, is another composer.
That's not why I'm advising the average composer to stay away from other composers though, although that would go some way to avoiding a certain amount of bruising and bloodletting (if not seething, festering jealousy and resentment).
I don't mean you should never speak to another composer - you've got to learn something, for starters, and I'd not have got much out of the composers who taught me if I'd sat there mute, or refused to turn up to the tutorial. And I've enjoyed social congress with other note scribblers on many occasions, almost never ending in physical recriminations (it helps if you manage to get enough drink inside you to remove the ability to land a punch, of course).
No, what I'm thinking of is the sort of occasion you can see quite regularly in any place where scccm is being performed (perhaps, here in London - actually, almost certainly, here in London - a mini-festival organised by the London Sinfonietta or the SPNM). The performances come and go through the day, people drift in and out of the concert hall, gravitating towards the bar, usually, and little clusters of conversation can be seen. And here's the thing: it's nearly all composers talking to other composers. If you go along to one of these things, it's actually quite difficult to meet anyone who isn't a composer. Sometimes you might get the feeling that the entire concert scene in London is really just an excuse for a lot of composer networking opportunities.
Now, if making a career's your thing, blah blah, networking's one of those things you do, sure. But composers (mostly) aren't going to play your damn music. Unless you're writing stuff for yourself to perform (and that's a subject I'll return to), you need musicians. Friendly ones, who know you and will be willing to put up with your ill-thought-out notation and ignorance of what their instrument can do, and will gently, kindly tell you how to change it to make it better. Musicians are quite easy to meet - just go to the nearest pub after the gig. If you make friends with them, they'll be only to happy to offer advice, and it's not that big a step from there to persuading them to run through something you've written. So stop talking theory with all the composers and start talking practice with the players.