I do. I track my reading on Storygraph because it motivates me and helps me keep up the habit when I hit a slump or end up with some uninspiring piece. I don't have to fumble for a new book to read because all recommendations and interests are neatly registered and organized. My progress is tracked and I can celebrate my success. I also have a huge library of digital books, over 2 thousand. By tracking I can keep a log of what I have and haven't read. Sometimes, after a long while, you forget the names of specific books in series, or where you were last off in a particular author's collection, etc. It helps with it all. But I don't connect or share that with anyone. Nor do I feel the need to push it on anyone. Friends and acquaintances are not that into reading as I am and they see no use for a social network about books, and I don't want nosy strangers rummaging though my reading history.

Probably just so you don't accidentally waste time unknowingly rereading a book.