A client once asked us a simple question about their platform: a user says they were charged twice, can you show what happened? We couldn't. The system knew the balance today, but not how it got there, because every payment had been written as an update over the previous number. The past was gone.
Reconstructing that history took far longer than building it properly would have, and parts of it were simply unrecoverable, so the dispute got settled on trust instead of records.
Now, on anything that touches money, we write every movement down as its own line (what happened, when, and why) and we never edit it afterwards. The balance is just the sum of those lines. It costs almost nothing to do on day one, and it is the one part you can't add back in later.
If your product moves money, you probably want to know whether you could answer that question for a payment from last March.