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’m glad it was interesting! I think we’ll all appreciate more variety in our diets.
The apples you mentioned are a good example of this. Apple breeders used to always breed the flavour away in favour of looks since that’s what sells. When one guy bred a tasty apple, only for his colleagues to make it tasteless again, he decided to brand it and enforce some quality control. Breeders were very skeptical, and few could imagine that consumers would care about what apple variety they’re eating - do you know what type of potato or cucumber you buy? But in the end, consumers proved willing to engage and branded apples are now widespread. Tenderstem broccoli has recently inspired Brassica breeders to start branding and marketing their new varieties.
I’m involved with some breeders trying to do the same with potatoes!