Not quite, but close! Molecular plant breeder here.

There is no set “limit” to flavour but it’s a complex trait that is easy to lose if you don’t select for it. If you breed for size, and don’t track taste, it’s very easy to leave the flavour-producing aspects unchanged, thus resulting in a “dilution”. Furthermore, you’re often actively selecting against flavour, indirectly and unintentionally, by selecting for shelf life - if something doesn’t ripen, it won’t over-ripen and spoil.

This is what has historically happened to a lot of produce but it doesn’t have to be the case - modern breeding lets us breed for flavour and nutrition too! Heirloom varieties can offer some reprieve, but for all their taste they tend to be quite unproductive and sickly (ofter “heirloom” means inbred and that does not produce very fit organisms).

Good news is, new varieties are being bred that have it all - yield, taste, and nutrition! It’s just hard to convince consumers and businesses to switch over to new varieties, as you don’t really buy according to the flavour, just the looks.

Greetings from the UK ;)

I know the coffee bit is bullshit (https://coffeeabout.com/coffee-consumption-by-country/) so likely the other stuff is too