Whatever floats people's boats. People have been setting up local video game tournaments pretty much as long as video games have been around, and this is essentially the same thing but on a grander scale. Certain genres, like fighting games, are all about the competitive multiplayer, so it's only natural that the best would seek out others at their skill level, and those who aren't that good would be interested in watching the best in action. And back in the day, games were about high scores, either setting a personal best or beating everybody else's scores on a public cabinet. I don't think the big deal our retro gaming community has made about people like Billy Mitchell is any less silly than people watching or obsessing over modern "e-sports" players.