I believe that most arguing over the internet doesnt qualify as debate, and consider it somewhat of a lost skill. Critical thinking/analysis is not undertaken by most people, particularly on the internet.

Debate is a cornerstone of democracy - to take the climate change example, anyone should be able to question it, and the evidence for it should be what persuades the majority of people, leading to a decision. In these cases, debate is a very effective mechanism. Unfortunately, people don't tend to engage and debate properly.

A good, reasonably relevant read (5 min) is Isaac Asimov's A Cult Of Ignorance, which I think goes some way to explaining the lack of engagement with debating.