[Ducky]

I wouldn't say that's true at all. there's absolutely nothing wrong with mono coloured from what I've seen. Plenty of the people I play against have been into magic for years and still run some mono-coloured decks.
the main issue i see with mono coloured is that it can a weakness sometimes.
say you had an all black, and they had creatures with protection from black. you're screwed.

I personally run a black/blue, blue and green.