> But it almost reads like a chess Grandmaster in the 90s telling up-and-coming players to not practice against Deep Blue because it will teach you bad habits.

No idea if chess grandmasters did do that in the 90s, but frankly it would have been good advice. Just as it is good advice today for up-and-coming players not to practice against stockfish, leela or whatever. Unless you are already very proficient in chess, practicing against those engines will teach you very little .

Gukesh, the current world champion, did not use engines for analysis until very late. I think until after he became a GM.