the eye can only handle so much at once. its much easier to get traction with one bright color than it is with two or three. if you're just going to go out there and say 'fuck it' then it doesn't matter. but if you're trying to pull off a coherent combo, its best to pair something bright with something neutral.
This is very good advice for beginners or anyone who wants to remain within the bounds of 'good taste'. This is the peacock thread, however. Check out Barims' view on your colour theory! The basic problem with the fit to which you were responding is that like too many, it just doesn't belong in this thread. Just wearing red trousers does not equal peacock.