I bet it wasn't anyone mad or anything, some people just like to clean up their lives - real and electronic, and may have decided to delete old posts/threads or something.

This is not a trait that runs in my mother's side of the family, but Dad is a "neatener and disposer of junk" and so I recognize the ability. He's an engineer, but after retiring, went to work for my uncle (my mom's brother) essentially throwing things away. It is as useful in business as it is in one's home!