When its snacks and BS while everyone gets hooked up and gets files off the local share to install SC2 for the nth time. It would take hours to get set up. Then more hours of play. We'd go for 10 to 12 hours sometimes, just to get things working.
We couldn't play any modern games, because every single person at the party would have had to have a Steam account or some license to the game, and have to log into it on my computers, then sign out when they were done... what a bunch of garbage. Nobody had their Steam passwords on hand.
With Quake3, you could sit down on any free machine and jump into a game instantly. I was also really surprised because some computers had the "official" Quake 3 purchased from Steam on Windows (friends who brought their own computers), some had the open source Quake 3 engine running on Linux, and some had official Linux clients... and they all worked together flawlessly.