You are essentially arguing that it is a virtue if something cannot be fixed when it is broken. But the truth is the reverse. The harder you make it to fix something when it is broken, the worse things get when it breaks.
People will always have the ultimate recourse of forking. There’s no conceivable way to take that away. There is no known way to prevent this nor do I think it’s even a good idea. Immutability doesn’t make any sense, except in the sense that the past can’t be changed, but that’s a scientific fact for every system.