Wild sunflower plants have a range of ripening times, seed size, etc. The problem also applies to farm animals. So domestic breeds of animals are missing a lot of the genetic information in wild animals. Many people remember the deliciously sweet, fragrant strawberries picked from their home garden. They were smaller than the ones available today, but they tasted and smelled better.
People buy with their eyes, so nice big, red strawberries sell well.
Plant breeders therefore concentrated on breeding big, red strawberries with high yield and good shelf life. In concentrating on these characteristics, flavour has been neglected. The point is that selecting for one characteristic can be at the expense of something else. One character can be accentuated while another is diminished. There are biological limits to what can be achieved.