When they say "stuttering is a habit", what do they mean by that?

When they say "stuttering is a habit", what do they mean by that? I have encountered that statement in couples articles in the past and recent post here. I don't understand and can't relate to that. When I have a block I feel that speech system in my brain is congested, and I don't have control over that. So how can stuttering be a habit, please someone educate.