For me that is a resounding yes
Which is why I emphasized the question was non-rhetorical. There are lots and lots of really good reasons to do it. It's been my experience in ten years of participating in this forum, though, that some of us -- and I myself am chief among them -- do things for a sense of security that we don't actually get value from. Those activities become burdens rather than enablers.
So I don't think it is a bad question to ask -- but I fully understand that a significant number of people, for a variety of reasons, do indeed get value in keeping notes about past interactions with people, completed projects, and lots of other things.