There are many ways to carry speech; monologue, dialogue, discussion… But as soon as you get two people involved… differences in points of view pop up; which is completely normal, and rightfully so; we’re not a world of homogeneous greys. Our upbringing, our surroundings, our own thoughts, and the events in our lives all influence the way we think.
Yet, there are ways to discuss that lead to better success; not in convincing, but in exchanging points of view, which lead to a healthy constructive discussion.
Say, “I only advise you of one [thing] – that you stand for Allah, [seeking truth] in pairs and individually, and then give thought.” There is not in your companion any madness. He is only a warner to you before a severe punishment.
Surah Saba (34 – 46)
Even if announcing an idea or a product can be done via mass media or in front of a packed stadium, the best results (and the most lasting) are from the word of mouth; meaning, from one person to another (as long as the product or idea is a good one). Then, if that person is left to himself to ponder, think about it a little, the wheels start turning.
Now, it is not only the environment that is important but the way the message is transmitted.
Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best. Indeed, your Lord is most knowing of who has strayed from His way, and He is most knowing of who is [rightly] guided.
Surah An-Nahl (16 – 125)
Unfortunately, a lot of debates, even if done 1 vs. 1 or 2 vs. 2 are done in presence of an audience. And even if it is informative for the audience, the speakers often adopt an attitude of “I must win the debate”. So the whole point of the debate is not to come out with the truth, but rather stump the other. It’s normal to deconstruct someone’s argument and point out what one finds uncompelling or inadequate, but more often than not, it turns into rhetoric.