On the logic:
In terms of pure logic, absence of evidence is indeed not enough evidence to PROVE absence. There are certainly going to be many people who lived and died who we have no evidence for.
However, in practical human endeavors we often have insufficient evidence to prove any option true or false and yet we still want to make a decision.
Very often therefore, in situations where we know which direction we want to play safe in, we speak of a "burden of proof". For example, when someone accuses someone else of a crime, the accused person is "innocent until proven guilty" and not "guilty until proven innocent". The reasoning is well-known.
Similarly, when it comes to writing an article about an historical person, if no one has any evidence that the person ever existed, we must surely place the burden of proof upon anyone who says an article deserves to be made?
But it remains true that there are many people who lived in the past who existed, and who we have no evidence for. We can not prove today whether or not any of them existed, and indeed we have nothing to say about them unless we make it up, or someone writing a website or book does it for us.
...So in practice we can't dedicate this Wiki's resources and volunteers to articles about "potential" people for whom there is no evidence.