Well then it looks like we still have a way to go. Because if this is how it should be "by design", it's not decentralized at all, not even close
Then what you are asking for is impossible. At some point, coders make choices on what they implement that has an impact on the protocol and the network. Furthermore, it is practically impossible to pretend that you can prevent people from arbitrarily choosing to point their clients to another blockchain. Forks will happen because of bugs, developer intervention, and even because a user has decided to make his own personal fork for whatever reason. There's always a game going on about how many people are going to join a given fork.
The only truely "decentralised" system is the universe. You can not roll back anything, time passes and the laws of physics take care of executing themselves with no possible changes on the "blockchain". No coin that is decentralised in that sense can exist. Cryptocoins are simulations of a universe, but humans are one level on top of it, and the protocol can not reach out and prevent somebody from fiddling with the controls. It would be like sort of Skynet world playing God with its own creators.
When these forks happen it is an alternate reality, a new coin.
To this day I refer to Vericoin as Vericoin2, because that's what it is.
The real Vercoin had a boatload of it stolen off of Mintpal
The real Nxt had 5% stolen off of Bter.
The issue is getting to a point where HISTORY can't be changed. I don't think that is impossible at all.
What you're not realising is that every fork is a separate HISTORY. And like you ask, history can't be changed because of it is cryptographically secured and guaranteed. That's the invention of the blockchain. But I can still copy the history book and start doing my own additions to it on my own version of it. Nothing prevents me from copying a history book, then keep writing it and make my own version of it. It's the nature of data. You copy it, and then you make what you want with it. You are essentially asking to stop file sharing. How is that working out for the lawmakers? There is no way to prevent people from going somewhere else and doing their own thing.
No you are taking this way out there.
No one is saying anything about adding to the history books.
I am talking about someone, or a group of people deciding to go with a chain that is not the correct one, one that is missing, say the 5% theft transaction off of Bter.
Thats what Im talking about. Not the universe or history books that I add things to.
What I'm taking about is stopping the ability of transaction getting
erased from a ledger, when EVERYONE KNOWS THE TRANSACTION happened.
I think this is in our future. I hope.