Deconstruction isn't bullshit, but we've been swimming in deconstructive and reconstructive narrative media for nearly half a century, and it has altered how we critique media so heavily that people don't see it as a distinct feature of their worldview. (Great example: Folks seem to love Rick & Morty, a deconstructive soft sci-fi serial, and also Steven Universe, a reconstructive soft sci-fi serial, both of which are running on a network which markets to youth, not literature postdocs.)
Kay, like Derrida, hasn't been unable to explain to people for lack of words, but because the enormity of the paradigm shift means that no number of words will necessarily suffice.
(Aside: If you are rubbed wrong by the first paragraph, in particular because you believe that reality is absolute or that truth is definable, then do not fear. You are merely having trouble overcoming instincts. Trust in mathematics; postmodernism arrived in mathematics in 1874, was completed in 1930, and is widely accepted by the mathematical community as meta-truth. Dissenters exist but necessarily must accept the meta-truth ("There is no one true foundation for mathematics.") to avoid being laughed out of the room.)