Not generally. There are some who I see as being intelligent people who's opinion I respect, and that sort of reputation (though I'd rather not use that word) can only come through a number of posts. However, I also tend to have a lesser opinion of those that I deem to post too much. Because if someone posts, in my opinion, too much then I can't believe that all their posts can have been of note - and quite frankly I despise one or two word answers.
As far as I'm concerned anybody, whether they have one or one thousand posts, can prove themselves to be intelligent, informed and generally nice guys. Post count is of no importance; it doesn't signify intelligence - only how often the person is willing to comment.
So overall I'd say its quality not quantity that counts; quantity isn't necessarily a good or bad thing; quality always is.