Said this on the basis of what TR podcast’s deep dive into the literature specifically stated. I agree you could say certain methodologies of training are polarized and those find their origins in many different disciplines farther back. However, the notion of polarized training wasn’t really developed until Selier’s observations of the data in his research.
Selier very clearly states that he simply sums up what coaches have been doing for decades its just that the research catches up with it. Thats normal.