The homogeneity phenomenon started in the 80's with the advent of cable tv (MTV especially). The internet just cemented a growing trend. I went away to college in 1986, and at that time the difference in personal style, musical tastes and particularly regional slang were enormous among kids from different parts of the country. I noticed that over the later part of the 80's that some of those differences started to erode. At the time I attributed it to MTV, as I said.