"The aim of argument, or of discussion, should not be victory, but progress." —Joseph Joubert.
As rightly said, it's not been the same in the twentieth century. Arguments today are a more violent, less informative and plain exchange of ignorance. Why? With the advancing age of information and all the people having access to information right over one's fingertips, one seldom asks questions to anyone and if one does, the social pressure of always being right or up to date comes into the picture and hence slight bigotry is observed in millennials.
When in an argument, humans often tend to stick to their beliefs be it right or wrong just because they've been sticking up to it till this very time. Accepting their mistakes isn't an option as it'd be seen as socially decreasing their value. Like one of my favorite essayists, T.S Elliot says "Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information?" In an argument, it's simply all about the information one possesses while sharing and accepting of others information is ignorance as no one is ready to budge and accept the mistakes their beliefs have. Whereas discussion is a friendly, stress free environment for like-minded people who don't have the pressure to be right nor they'll be judged by their unawareness regarding a certain topic and as they'll be free to ask all sort of questions to the fellow people in the discussion, their doubts will get clear and they'll develop a better understanding of the topic that is discussed.
Hence one can see how a good environment and a discussion group can indeed exchange knowledge and enhance their understanding of new things rather than that of an argument where one makes a stubborn stand over a topic and isn't motivated to be flexible and more open to new thought processes.