There is only one person that can rule that out, but since this is their statement on the subject I would take it as authoritative unless there is a better source.
You probably have a substantial subset of the people on that list on HN, so it might be possible to recover a chunk of the 'paper era'.
> I would take it as authoritative unless there is a better source.
I'm not doubting the authority on the balances; it's the correlation to the number of checks I'm querying - high balance doesn't necessarily mean high number of checks, especially since the checks can have different values.
I received two checks in the very early 2000s and my name isn’t on this list.
For the record I cashed both and have zero regrets. At the time it definitely felt like the right thing to do as I am not into collecting tokens.