Why are sunflowers so tall?

I'm a landscaper who grows sunflowers for clientel and happen to know a lot about them. sunflowers are originally thought to have come from either Russia or North America. the mammoth sunflowers grow fast and become tall not because they want to be noticed but because they need to have height in order to collect sun. Furthermore as the sunflowers grow the bottom leaves naturally begin to die off as new ones emerge from the stalk. Also sunflowers prefer to be fed, while it is not necessary, they seem to flourish better in areas with a well propagated ground. given these factors a lot of scientists and biologists believe that sunflowers get they're height because they are used to growing in crowded spaces among other plants. the sunflower itself does not seem to have a long evolutionary history because they have little to no protection against wild animals (except for a thick nasty tasting stalk and plenty of height) and the only protection they have against insects is tiny hairs that grow along the stalk. most of my clients would complain of diseases on the stalk, leaves, and seed. This suggests that they're immune system is fairly weak.

Most sunflowers are annuals not because they're seeds can't last the winter, but because animals such as birds and mammals constantly eat them. the smaller dwarf sunflowers usually have more volunteers than my mammoths but that could be the small seeds being hard to find by birds, people, and wild animals.

another bi-product of the sunflower is sunflower seed oil. this was discovered by people when they would cut the stalks down and shave the leafs off. today it has many uses but because it drips slowly and they're is very little per plant it can't be bought easily as a wholesale item. the seeds themselves get coated in sunflower seed oil which is why they often turn a dark shady brownish color after sprouting stripes.