Why do academics still travel around to meet each other, go to conferences, etc., to the degree and frequency they do when they could do all of that online?

Indeed, why do we still have universities, even? The vast majority of things people generally go to university for, save for experiments in the natural sciences, could easily be done at home. This realization is inevitable, and I suspect that the trend where people take more and more courses online and learn things on their own with the help of the internet will only continue. It would free up a lot of time for people who otherwise teach so that they could do research instead, by just referencing a YouTube video of a lecture rather than repeat the lecture again and again year after year for such a small amount of people each time. So the question becomes, will the very idea of academia and having universities begin to loose validity as the years or decades goes by?