The claim that education outside vocational schools has little or no practical benefit is so obviously wrong that there seems no need to actually rebut it. Just let it stand.
It is relevant to note that some people do not learn well in formal learning environments, and this is probably where the belief by some that "book lernin` tain't worth much" comes from. While it is true that some people can graduate from an institution of learning having actually learned little, the generalization that this is true of everyone is obviously false.
--Percy