May I point you towards Friendly Carnivore

Plants can't run away so they defend themselves with chemical warfare. Most of us can detoxify a lot of the common food plants, but some of the accumulated toxins get most people in the end — a lot of the diseases of aging are effects of the poisons plants use

At the lowest end they block nutrient absorption like tea blocks iron

As you say, the more you know the less good they seem

If you're intolerant of some of the common food plants (for me it's wheat and cocoa. Apparently my ancestors didn't have wheat until 6000 years ago, and cocoa came with the Colombian exchange so no surprise many of British stock can't handle all of those plants' attacks