This is true! I used to be a lurker before I got the courage to sign up.A lot of folks sign up for accounts and never post. But that's true of the vast majority of internet forums. I've been a lurker on a couple of other boards myself.
What used to drive me up the wall were spam accounts, which would find ways to shoehorn links into the body of their posts like normal members. They became pretty easy to spot, however.