that's not the main reason.

it's more because that shit is there forever. so if it's impossible to inspect and trace payments now, that don't mean it remains so five or 10 years from now. btw, chainalisys had some monero tracing like years ago.

so imagine if we'd have a perfectly preserved crime scene from like 1785 (and multiple, perfect copies of it!) and we can unleash the full power of today's forensics on it.