Good point, but this would apply to ongoing debate. In this case person jumped in into conversation with the premise "I don't have time to listen to arguments b

Good point, but this would apply to ongoing debate. In this case person jumped in into conversation with the premise "I don't have time to listen to arguments but here's mine opinion". The thing is, all the theories of communication for persuasion (Social Judgement Theory and Elaboration Likelihood Model mostly) boil down to "hear your audience". If you really want to convince or persuade anyone, the starting point is to understand what's in the head of the audience you are trying to persuade. It's not often easy to get this information, so you start by expressing your views and carefully listening to the answers and arguments of those who have different views. So if you have a chance to get the arguments in advance – before communicating your opinion – it's a blessing. It's a free lunch for persuasive communication. You're given people's opinions and arguments on the plate, basically. And here this free lunch is thrown away just to be replaced with "here is my opinion and I don't care about arguments" communication style. That's not a starting point for debate at all.