Did you read the slide? It doesn't make the argument you are responding to, you just seem to have been prompted by "Math".
If you look at the slide, the subtree of correct answers exists, what's missing is just a way to make them more prevalent instead of less.
Personally, I think LeCun is just leaping to the wrong conclusion because he's sticking to the wrong tools for the job.
Then I disagree with you.
But I'm even less sure what conceptual reasoning is.