It stops then we learn that conversations need to be kept "on topic." But by "on topic" that doesn't mean the conversation stays on one topic. It means that each progressive comment is associated in some way with the previous one. By that definition, NT conversations don't just progress, they evolve, meander, and end up going all over the place, which is something that drives most of us stark raving mad.
Thus, for the most part, we sit there and listen for cues or openings (comments that are closely related enough for us to interject with our own special interests), and once we do "get a word in edgewise," we're not likely to let go of it easily.
One of my sons is extremely adept at seeing "connections" between something being talked about, and one of his few special interests. No matter what we're talking about, he'll manage to find a connection between the topic and video games, origami, or computers.
Wait until you have your opening. THEN no one won't be able to shut you up! 
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I'm not likely to be around much longer. As before when I first signed up here years ago, I'm finding that after a long hiatus, and after only a few days back on here, I'm spending way too much time here again already. So I'm requesting my account be locked, banned or whatever. It's just time. Until then, well, I dunno...