This is inaccurate and borderline dangerous advice. The output of a KDF does not contain more entropy than the input. You cannot "create" entropy with a KDF.

This is inaccurate and borderline dangerous advice. The output of a KDF does not contain more entropy than the input. You cannot "create" entropy with a KDF. Sure it _looks_ random, but no actual randomness was added during the process. A KDF adds some security against brute force attacks by making them more expensive, but it does not add entropy, it does not increase the search space of a brute force attack.