> 1. Let’s say we pass a law that prevents offers from being revoked. This will make hiring much harder and increase 5 rounds to like 10 and involve many more committees and even then most candidates other than sureshots getting rejected.

The problem isn't quality of candidate, the problem is unknown business changes. Sitting on your hands for 10 rounds vs 5 won't fix those unknowns.

Certainly companies might respond this way, but it makes no sense and won't actually prevent them from giving an offer to someone in the face of unknown layoffs.