Another useful property of this technique is that it makes the bitcoin blockchain robust to 51% attacks.
That's mainly helpful if there isn't much growth in the user base between the fork and the attack.
In the very unlikely event that there was an unrelenting 51% attack that rendered the bitcoin network unuseable, would you prefer migrate to a network that uses the current blockchain, or a network that uses a copy that is 1 year old?
I believe the economic majority would migrate to a new network built from the most accurate and current version of the blockchain of the coin with the largest market cap.
This is what I mean when I say that the value of bitcoin is in our shared agreement that blockchain is accurate.