Of all the true geniuses I have met none are "on the internet", or if they are, are passive observers. They tend to be too busy doing amazing things than writing about it. I have no doubt that each would be a "superstar blogger" if they so decided to, but I highly doubt it's ever going to happen.

In private, they share in confidence with people they trust and organizations that they work with who treat such knowledge as competitive advantage.

The thing is, once you are at the top of your field, what incentive is there to share if you are still making personal breakthroughs on a regular basis? I don't see any.