Now that I think about it, they were probably inspired by the traditional “three sisters” agricultural technique of cultivating beans, squash, and corn in the same plot of soil.
Here is a good book on that subject, if anybody wants to do some really in depth study on the traditional three sisters method, which in modern terms would be considered a form of permaculture or regenerative agriculture. The three sisters technique works over a course of years in a no-till plot, each crop fixes a different set of nutrients and feeds the others in turn.
In order to really see the unique benefits of the three sisters approach, you would need to actually practice this technique yourself in a no-till plot.
So again, in this buildasoil compost, the pinto beans are really just a source of green matter, very similar to using any other nutrient rich crop residuals. Fine, but not worth paying extra for.
edit- I’ll snap a picture of that book I mentioned and add it to the post shortly.
edit 2 years later- the book is “Permaculture: Principles and Pathways Beyond Sustainability” by David Holmgren.
shoutout @cannabissequoia for the reminder
quick review-
(I read the practical stuff about permaculture technique, and that was informative for me.
it is more focused on farming than gardening. it doesn’t have much about adapting these techniques for use in an existing garden.
there is probably a more concise book about permaculture out there.
I skipped a lot of chapters that strayed off topic to discussions about the sustainability of industrial farming and other stuff.)