Yeah I needed it for when I (mostly) left Facebook. Also even when on any of these systems free text searching your old posts just sucks. This really helps me find content from way in the past that is in the archive. The Friendica archiver lets one keep a running archive of their Friendica account so it can be used for more "up to date" searching without extracting a whole new archive periodically. I haven't written anything that does that for any other social network though.