is being condescending ever a good tactic?

[MusicLovingAtheist]

I have been thinking about this question. Over the years I have used the internet I have seen many people that try to exude a patronizing superiority to people they're arguing with. Perhaps this is a good way to assert dominance over the other person, weakening them mentally. Perhaps it is uncivil and the goal of a discussion should involve treating the other person inclusively as an ally for reaching a common goal, to understand the meaning of what the other person is trying say. It seems that being condescending or insulting are childish things to do. There's an old saying - don't argue with an idiot because they will bring you down to their level and beat you with their experience. So if using these methods is so futile then why do we use them in the first place?