For one thing, consumers favoring the convenience of supermarkets means choice gets limited to what large scale agribusiness can supply profitably. Local species and cultivars whose horticulture does not scale well, whose harvest can't be mechanized, which have a short ripeness window, which only produce crops rarely or under ideal conditions, and/or are too delicate to transport over long distances, don't fit with agribusiness production and supply models (nor with the patented GM sterile seed industry that is ever more forced on small scale farmers).

If you negate that list, you get a list of traits agribusiness tries to breed into more conventional plants often at the expense of optimal tastiness.

Yet the "reject" plants might be super delicious and perfectly suited to local soil and climate conditions and to traditional agricultural practices and regional cuisines...

In Malaysia as a child the roadside markets offered incredible local fruits like tampoi, certain distinctive cultivars of mangoes, langsats, salak, mangosteen, little-known species of durian and other jungle fruits, and many others that are much harder or impossible to find today. (Although the commercial varieties of mangoes, durian etc. are still very good if you know about seasonal variations and exactly where they're grown; and, according to my palate at least, the fresh produce available in S.E. Asia still far, far surpasses the range and quality available in northern Europe.)

It's a mix of a lot of things. Prices. Convenience. Lost of knowlegde about food and cooking. The family split. The mass food production. Marketting and advertising. Improvment in chemistry. Cultural shift. Mechanization. Offer and demand. Glibalieatio. Demography. Like any complex issue it doesn't have one only cause.

I know I can buy so-so apples any time of year for very cheap. But I can also buy very delicious apples in season for a higher price. I can't say if the free market has spoiled my food unless I know the quality:price of apples in the past. I somewhat struggle with the option between poor:cheap and delicious:expensive, but overall I think it's best to have more choices and have confidence in making the decision for myself.

You know the season of apples, which makes you part of the 1%.