I just compared the helpfullness of lambda calculus to that of Turing Machine. I believe both have some value. Perhaps you are right that mine comment could discourage people to learn lambda calculus - and I should formulate it a bit more carefully. But I just tried to be honest.

Lambda calculus was quite nice, but it is too low level to be any practical and the interesting parts start when you learn the extensions to the lambda calculus like the F-system (where you get the ultimate polimorfism).