Agreed - Black shouldn't worry about a knight for bishop trade there.
Besides - that's Black's bad bishop, anyway. If White is determined to exchange, Black can say, "Thanks, White, for removing my problem piece. You're too kind."
Agreed.
I can see a Sicilian coach arguing though ...
'Just look what happened to your c-bishop in that Caro Kann line there! Do you want that? In the Sicilian you'll get to keep your two bishops and gradually turn the tide in the center and your two bishops will Wreak Havoc on white. Forget the Caro!'
Which has some validity. Black might really get that in the Sicilian some of the time.
But the Caro-Kann is very much in business.
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Is there a paradox?
There are many in chess including in openings.
The coach might do better to say something like 'avoid dogmatism in openings. Don't fill your mind with syllogisms about 'two bishops'. .'
There are many ways to guide your play.
But a lot of the game is about figuring out good moves for the situation in front of you. If you're having to evaluate by 'go to's'' instead ... uh oh ...
there goes the learning curve ...
Agreed - Black shouldn't worry about a knight for bishop trade there.
Besides - that's Black's bad bishop, anyway. If White is determined to exchange, Black can say, "Thanks, White, for removing my problem piece. You're too kind."