Good answers. Learned a lot.
Lol at the game too:
It's hard to become an IM! And when Dan was a young, active player it was even harder. There were very few opportunities to get FIDE norms in the U.S., so many ambitious players went to Europe and bummed around the tournament circuit, staying in cheap hotels, living on beans and sausages, and playing in as many tournaments as possible. If you wanted to get married and have a family, or start a career in the "real world", chasing norms around Europe wasn't an option.
At his peak, I believe Dan was rated somewhere USCF 2350. That's stronger than 99% of the rated players in the U.S., more than strong enough to be an excellent, authoritative teacher. But he may not have had the single-minder drive to get his rating higher than that. In fact, if he was beginning to have success as a teacher, he would inevitably have to give up some of his playing ambitions.
This is a similar to the "I'm 30, can I become a GM?" topics that keep popping up. Players just don't understand how hard it is to advance once you are only playing other masters. There aren't many gift squares, much less pawns, much less pieces like at amateur levels.
And once you do get an advantage, they don't fold like a cheap suit like an amateur, they double down and fight harder.
"At least an IM," indeed!
I find it amazing how strong players of Dan's generation (and before) became without any computer help. Those players had to rely on books, self-analysis and help from fellow club players. Perhaps I am only speaking for myself here, but it almost feels as if we have become a bit lazy... We want quick shortcuts to becoming GM's by watching a couple of videos and reading a book. Those players probably understood (more than anyone) what it took to become really good at playing chess.