I don’t think the medical community has believed as the article claims for nearly a century.
Most animal brains have three very different organs in the brain: the cerebrum, cerebellum, and the limbic system (which itself is further divided into numerous differentiated types of tissues)
This isn't about organs but the gene expression that is used to create the organs.
TFA refers to the evolutionarily history of the brain, not the specialised functionality of different parts of the brain.