Honestly...I don\'t know if there was any relevance in doing so, minus the curiosity factor. The contestant picked clues at random, so there was no advantage there in knowing a doctor\'s field of expertise. However...
Stay with me on this one, a lot of rambling speculation to follow...
I haven\'t watched an episode in years, so I can\'t remember, but if I am remembering the game correctly, you post a revealed (and incorrectly guessed*) clue to a doctor whose area of expertise has been revealed, it could make the game a little too easy and remove the challenge and mystery. Granted it poses a strategy if you know that Dr. Nick Riviera has a Ph.D. in biology, and a question about chlorophyll comes up. Again, it could also make things a little too easy.
*Or did this put the clue out of play?
And if none of that made any sense, then they did it \"Just because\".