Because it doesn’t seem to matter currently if you play ranked games or casual games, the general experience tends to be the same. But one has numbers and things to go with it. You still get people playing to win in casual games and you get people dicking around having fun in ranked games, and the ranks don’t necessarily indicate how they play as a team and a whole bunch of other things that make it less than ideal.
I was also there but it’s not a really good system when scale up. If you are from the same era, and if you did not own a clan server, they can kick you out for whatever reason. (Like killing a mod one too many times.) And for competitive games that really doesn’t work well, that’s why old server has that after round auto balancing mod, it shuffles player around base on how they performed. A fake way to try balance the team. Ie. I was kinda decent capper for 3wave ctf, grenade rocket jump and all that. So if opponent doesn’t have a good sniper or also decent enough capper, I can usually win the game even when our team is a bit short on players. Then when auto balancing come around to balance players, it actually make it less balance.(you also can’t dial it too much that you got spawn camped and thus one side of player just quit to find another server.)
And it also not helping if you go to a clan server and the clan all want to stay on the same team. Which often leads to players go in/out frequently.(that’s why later on GameSpy can even show match status so you can choose to join or not.)
A well managed server pool and MMR system helps resolve all those issues, and scale up really well.