That's sadly impossible, because the brain, as a limited number of cells, cannot store infite data. The problem lies in the people observing them, but you have some fun mechanisms (and a few of the commonly known fallacies and biases) at work here, that can all contribute to that perceived effect/illusion. Consider the following ideas:

- people can be slightly better than a given random observer, because they learned and prioritise to pay attention. They are better at recalling memorable and minor details, especially in short term memory and in memorable situations that a lot of people share long term. They will still forget long term information that is irrelevant.

- any such person and also observer can easily talk themselves into the belief that their skill must be absolute, especially since the observer will largely only test from his own inferior dataset.

- once the belief takes hold (because people love a good story), observers tend to look less for flaws and more for further confirmations to keep mythologising people.

It is debatable how much of his memory feats are true. many of these claims are aphorical.

I would imagine that such people stay off opine and commentary style forums because their instant capacity to recall authoritative sources makes wrongful and derivative discussion tedious. To some extent, with the speed of LLM search and recovery today, we might all be heading that way. Indeed, interesting HN traffic of late appears to have waned. No doubt someone will say I'm hallucinating and all's normal. No, I'm not hallucinating.