Tig, I think we all have certain combinations of letters like those you mentioned that automatically provide a handful of words whenever they appear. I also agree that varying forms of autism might have an advantage in word games, although I'm sure you'll agree it's unlikely that all of those who get all the words every day are autistic to some degree.
The rare words that most of us know are either relatively, but not totally, uncommon words, or words connected with a specialist interest. For someone to retrieve every possible word from his or her brain every day, very often with 100% accuracy (which means they never incorrectly play an invalid re- or -er word, a mistake that I'm sure most of us make) is, to me, simply not credible.
However, if there are indeed people who are genuinely brilliant then I offer them my sincere apologies for doubting them.