The argument about Hans’ ascent is that:
1. It was late relatively speaking. According to the report, elite chess players reach GM at a younger age than Hans did. They essentially claim that if you haven’t made GM by early teenage years, you won’t reach the very top.
2. It was uneven, with several plateaus. According to the report, other rising elite players show a smoother ascent without the plateaus.
I don’t know enough about chess to assess the veracity of the claim, but it doesn’t really align with other fields. Many/most elite athletes were dominant as youngsters, but there are many examples of late bloomers. I work in music; there are many elite musicians who were child prodigies, but there are also many late bloomers working at a high level.
It makes sense to me that if Hans became as obsessed as he claimed and worked as hard as he says, he may have made the leap. I don’t see why chess would be so different than any other field to make such growth so implausible.
That said, there’s a lot of smoke and now it looks like they’re scanning for anal beads, so what do I know.