Well, I think that would sevearly inhibit future development. Scaling on bitcoin has been a delicate game of optimizing every bit that gets recorded, but also support future developments that dont even exist yet, there is no undo button either. New signature schemas and clevar cryptography tricks can do quite a bit, but when you slap another layer of cryptography on you will inevitably make things worse in the long run.

Histories biggest bug bounty is sitting on the bitcoin blockchain, if it were even theoretically plausible to crack sha-256 like that then we would probably know, and many have tried.