Logs aren't proof.

Almost any system can show you a log. But a log that you, an insider, or an attacker could quietly edit isn't proof. When the stakes are a regulatory finding, a lawsuit, or a criminal case, the question isn't whether you kept a log, but whether you can show it was never changed. What clears that bar is a hash-chained record: change one entry and it breaks the chain, and the break is plain to see.