I wasn't around when points were introduced, but apparently they significantly improved the site quality in a couple of ways:
1. There were far fewer CDs with the new (current) system, as people used to join a very large number of games, play a few years, and just drop out of the games in which they weren't doing well. They'd only continue to play games in which they were among the leading powers; obviously, with so many dropouts, even those people who stayed in games had to deal with extremely unbalanced positions. With the point system effectively capping the number of games a person could join at once, people didn't join dozens of games at a time.
2. The point system allows for sorting by player experience/quality. Higher-pot games tend to have better players, because only they can afford to join such games. So new players don't join games in which they're completely outclassed by experts/veterans, and experienced players can start games and be confident that all the players will be familiar with the rules, have a reasonable grasp tactics of tactics/strategy, etc.