No, that's commonly made up thing coming form bitcoin where "balances" don't exist and the state of the ledger is defined by chain of past transactions. It is a design decision not a fundamental rule. It does not apply to the XRPL where each closed ledger has to follow all rules and contains all information to make forward progress. For example if a balance would be made up it would guaranteed violate a rule now (in the current ledger) there is no need to know the past transactions because if you add balances that would change the sum of all balances which obviously violates the rules. So form that point on each following ledger would be obviously and known in real time to be invalid. In reality ofc that cant happen because the software would simply not include a transaction that causes the invalid state. If for any reason there would actually be something considered "wrong" in the past it would not have any effect. The system is the code itself all participants agreed on running the same code and agreed on that what the code deems valid is valid and unchangeable forever. A bug can be fixed but what it caused in the past cant be. So the whole validation thing is useless it was validated already by the rules (the code) that was running back then. Validating it again with a bug fixed version of the code is useless. Just like if you would find an error in the bitcoin blockchain that validated fine with the version from that time. So what? it doesn't matter it cant be changed and if someone sends you bitcoins he only has because of a bug how does that matter if it don't change anything in the presets? You don't have to trust that no mistakes where made in the past you only need to trust that the past cant be changed to rely on the system in the presets.

Here's an example how you can validate the current state without knowing the past.

Imagine there are 100 coins made form something that does not exist beside in these coins. Someone wants to pay something to you using 2 of these coins. Do you need to know where he got them from and where the person before got them from and so on? If you know there are only 100 in total. (state is public) And no way to change that. (rules/code is known) And you know that if you take the 2 no one can force you to give it back. (transactions are irreversible) Then no, you don't need to know the past transactions at all. Maybe they where stolen in the past a thousand times also lost and found by someone else many times. Does it matter? Not at all.