When my grandparents told me that chicken tastes less good nowadays I thought they were just old and had lost their sense of taste. Actually they were right though.
Also anecdotally, I haven't found any other fruit or vegetable that exhibits such a drastic contrast. Maybe persimmons, but I haven't had that many supermarket persimmons. For most fruits and veggies, I've found the supermarket ones tend to taste roughly the same as garden grown ones. Indeed, sometimes I prefer the supermarket version, e.g. for apples.
[1] https://www.sciencedirect.com/science/article/pii/S1658077X2...
Those varieties have mostly out competed everything else in farmers markets and supermarkets but if you buy seeds online from specialized stores and grow them yourself, you can unlock an entire universe of flavor. Personally, I've never found a supermarket fruit or vegetable that tastes as good as the ones I have grown or eaten in countries with less industrialized farming, with the exception of designer varieties like cotton candy grapes, cosmic crisp apples, or sumo mandarins (though their quality is rapidly falling as they go from coddled breeding labs to industrial scale). I don't think I've had a "proper" strawberry, blueberry, or raspberry since I moved to the United States.
[1] https://science.sciencemag.org/content/336/6089/1711.full
I suspect this will be more of a trend across the US. Every time I visit back home in KS I see more people at the farmer's market there, more stuff in the supermarkets that's trying to regain some farm to table authenticity.
If I had to quantify it, I'd wager that fruits and vegetables from farmers markets are from 10% to 20% better than what you'd find in a supermarket. Co-ops can be as much as 10-50% better but growing it yourself with proper varieties is easily 200-300% better, especially here in California. Tomatoes with so much flavor that you can taste them through a tablespoon of ranch dressing (not that you'd ever need anything more than a splash of olive oil and a dash of salt with home grown vegetables).
(So are they afraid that if they start selling truly delicious tomatoes in summer, they will no longer be able to sell mediocre tomatoes in winter?)
https://www.wired.co.uk/article/why-do-uk-tomatoes-taste-bad
The tasty plants still exist, you just have to find the right sorts. They won't be found in your local grocery though.
It is probably breeding practices here, to promote attributes other than taste.
That's a factor, but also stronger flavor isn't considered a positive thing in chicken in the US.