Oh you mean like, sugars and starches - the most toxic constituents of the modern diet.You jump pretty readily to a conclusion that isn't in what's said. "Plants" covers a diverse group of foods, some of which are the most nutrient rich available to us.
You can eat nothing but potatoes, which are filled with starch, but a diet filled with plants is much more likely to involve a rich variety of very healthy foods. Some of these foods would be things like spinach, kale, carrots, beetroot, beans, sweet potatoes, blueberries, apples, bananas, strawberries, buckwheat, avocados, courgettes, onions and peppers.
There's definitely starch and sugars in these, but you'd be hard pressed to eat them to anything like a toxic degree. To get them to a toxic degree, you'd need to eat processed food in quantity, which isn't what the maxim, which is undoubtably glib, is suggesting you do.
I agree with your comment about food being used as yet another status symbol, and I generally find that a particularly unpleasant and tiresome way to treat something as essential as eating. I'd disagree that Pollan is the patron saint of foodies, though. He's perhaps the patron saint of plant-eating, slightly ascetic or vegan foodies. He's certainly not the patron saint of the paleo or keto crowd, both of which are very vocal and often produce very obnoxious members of the "food as status symbol" group.
Out of interest, what would you recommend as a good, healthful diet? As you can probably guess from my reply, I think Pollan's maxim, which is certainly glib, offers a good working basis for a healthy diet.