I think the point is that nutrients like trace minerals have to come from somewhere. And if they are lacking in the soil, they will be lacking in the plant.
Molecules that would be synthesized by the plant from trace compounds or pathways that require trace compounds would be lacking in the plant if it's lacking in the soil.
So if the soil is lacking in those trace compounds, there will be a gap in the output nutrients when we consume the plant or vegetable as food. This goes up the chain and is a reason why grass fed livestock is higher in Omega 3 fatty acids due to the differences in the feedstock.
Same as how farmed salmon don't have orange flesh because they do not consume the same food sources as wild salmon. So their flesh lacks the molecular compounds that result in the natural pigmentation that results from consuming organisms that consume krill.
Commercial fertilizers replenish the compounds that are required for the rapid cellular growth of the plant, but do not sufficiently replenish the trace compounds that would be in the soil from natural cycles of growth, decay, and recovery. There is also the factor of biodiversity as different plants, animals, and fungi will enrich the soil composition in different ways through their natural lifecycle which does not occur in monoculture industrial farming.
(Not critiquing modern monoculture industrial farming as its efficiency has allowed for huge growth in the human population, but it's clear why it would result in less nutrients in the output over time as the soil itself becomes depleted)
Sure, lack of nutrients will stunt the plant in some way, and will reduce the production of some plant compounds. But the original comment's logic is just too simplistic. You can't then safely jump to the conclusion that the lack of nutritional value in plants is primarily due to the reduction in these plant compounds
The main drivers could very easily be due to a variety of other factors. Like the sibling comment says, it could for instance be changes in agricultural practices (like the plants growing faster) b/c farmers naturally optimize for volume and not nutritional value per-kg or per-calorie
There are just a million other variables at play - and the nutrients in the soil aren't intrinsically the limiting factor for the nutritional of plants - b/c what's nutritional is fundamentally different
Molecules that would be synthesized by the plant from trace compounds or pathways that require trace compounds would be lacking in the plant if it's lacking in the soil.
So if the soil is lacking in those trace compounds, there will be a gap in the output nutrients when we consume the plant or vegetable as food. This goes up the chain and is a reason why grass fed livestock is higher in Omega 3 fatty acids due to the differences in the feedstock.
Same as how farmed salmon don't have orange flesh because they do not consume the same food sources as wild salmon. So their flesh lacks the molecular compounds that result in the natural pigmentation that results from consuming organisms that consume krill.
Commercial fertilizers replenish the compounds that are required for the rapid cellular growth of the plant, but do not sufficiently replenish the trace compounds that would be in the soil from natural cycles of growth, decay, and recovery. There is also the factor of biodiversity as different plants, animals, and fungi will enrich the soil composition in different ways through their natural lifecycle which does not occur in monoculture industrial farming.
(Not critiquing modern monoculture industrial farming as its efficiency has allowed for huge growth in the human population, but it's clear why it would result in less nutrients in the output over time as the soil itself becomes depleted)