I've heard this take a lot, but I really think it has a lot more to do with how we treat our soils. American agriculture is obsessed with sterile soils. But the MAJORITY of plants in the wild get the MAJORITY of their nutrients from mycorrhizal fungi. Something which is not present in sterilized soil.
They are quite fragile too. Not only are they killed by pesticides/fungicides, but even artificial fertilizers hurt them because plants rely on lack of phosphorus for them to start the signaling process to hook up with the fungi. Artificial phosphorus is much less bioavailable to plants, but its presence is enough to make them not start that complicated chemical dance
The mineral content of our vegetables has declined by over 90% since 1914.[0] I'd find it hard to believe this lack of nutrient doesn't also have a massive impact on flavor profiles
[0] https://www.scientificamerican.com/article/soil-depletion-an...