I remember the member directory and how easy it was to find people that you had lost touch with or were just curious about because of their reputation or interests. They probably scrubbed that because of privacy and cyber stalking which still goes on even today all over the internet. I've been cyber stalked before and in a way am glad that not just anybody can go poking around in my profile and use that info to track me down and harass me. Just my two cents.
What I really miss on Yahoo from the turn of the century is how cool and active the groups were and how mods of successful groups didn't put up with any spam or bs.
I once had a halfway decent video game group on Yahoo around that time period and it was a lot of fun but, it was also a lot of work and no one wanted to help out save for one guy who was really cool and new HTML code.
Later I became a mod on the largest emulation group there and had lots of work cut out for me and on top of that I had to do the usual moderator tasks and after a while it just got to be a babysitting job so, I had to step down. I swear I will never be a moderator on a group or forum again if I can help it.