No one cares that the Bcash ledger goes back to 2009 and the Litecoin ledger only goes back to 2011.
If we use Peter R's argument on that subject, then the noble metals (silver and gold) are a billions year old blockchain with built-in pruning, thus making anything cryptocurrency related a joke. It was a very illogical comment to make by not admitting the ledger of humans has been metals for thousands of years and it's NEVER been the scamchain. So if he claims the oldest ledger wins, then metals win, not any of this garbage.
Indeed, gold did serve mankind as a sort of "analog ledger." Gold's special physical properties (scarce, durable, divisible, fungible, transportable, etc.) made it apt for this purpose.
But I don't think the "oldest ledger wins" will be any sort of rule of thumb. A ledger only "wins" if the people who give it value (those whom accept it in exchange for their goods or labor) continue to value it. If it is widely believed that the distribution of money on that ledger is "sufficiently unjust," then people will work to discredit that ledger in favor of replacement, if a possible replacement exists.
Imagine a world 50 years hence where "bitcoin whales" wage war and spread destruction, while the economy limps along because everyone is indebted (in BTC!) to these whale warlords. In such a future, it would be in the people's best interest to work to abandon the bitcoin ledger that is both the source of the whales' power (to fund war) and the root of their problems (due to debt). And so a new cryptocurrency ledger would emerge as people abandoned the old.
I think what's happening now is a slow discrediting of the fiat ledgers, as value shifts to the crypto ledgers for similar reasons to those I described above.