If anything the fandom has become more generalized, commercialized and less intensive. My grandfather and his friends used to literally bellow at the TV on Sundays as if he was there live and they could hear them, and they literally wouldn't give you time of day if you were a Bears fan, because basically everyone who watched football had also played it at some point in their life.

Now, because of gambling, even lazy nerds are able to get in on it, but their amount of individual dedication to any given team, or even a single sport itself is not there. Sports may be the most important aspect of people's lives, but people have never been more adjacent (as opposed to participants) in sports.