Why?

Because claims that one singular concept or idea can explain pretty much everything in life have, historically, been quite false. Worse, such claims tend to attract people who like to have one simple solution for everything, or like to have one single thing that's root of all evil, or like to have one simple explanation for everything, etc. The damage such people can incur, especially when equipped with a grandiose enough concept, have (again, historically) been quite incredible.

Upon reflection I believe polarization helps to draw attention.

We love black and white as species. Nuances get lost way to often.

Thanks for explaining!