I think that we have a problem here. We're using two different definitions of "suck." Compared to tournament players, very few if any casual players such as myself don't suck. I'm not sure that tournament players are a good basis for comparison, though, because by that definition the large majority of players, even the large majority of people who play consistently, suck. In particular, we just defined "suck" and "casual" equivalently. While valid from a certain point of view, this is both inflammatory and useless. We already have a word for casual players. It's "casual."
You could reserve the term for people who really are bad, and by bad I mean really bad. "Suck" has pretty strong connotations, so I'm not sure that using it too liberally really communicates the normal definition. Congratulations, almost everyone sucks in comparison to you.
By the way, I object to the use of the term noob here, too. A lot of casual players are not noobs; they have been playing on and off for years. They may not be tournament players, but there is a world of difference between the normal casual player and a true noob.