Naftush – perhaps part of the problem is that gedolim of old lived in an environment where leisure time was minimal if at all present, where hobbies were reserved for the rich, and where they weren’t asked to determine how their followers spent every last minute of their time.
As an aside, Some gedolim did have hobbies. My ancestor R’ Yom Tov Lipmann Heller the Tosfos Yom Tov we know was a posek, halachist, kabalist and wrote a magnificent commentary on the mishna. But most people do not know that he was a proficient astronomer and mathematician. He became well known for this over time and even drew the attention of non Jewish scientists.