Well, that's because they
are hormones... Plants produce these hormones on their own; it's part of their gene expression in their regulatory system of growth. If you are extracting your hormones from a natural source like: coconut water, aloe vera, willow twigs, seed sprouts or whatever the natural source... do you see a harm in that? That is up for you to decide. Now this process begs some questions... Since plants produce these on their own, do they need us to give them these hormones? No. Can we manipulate plant growth with well timed, small applications of the
right hormone? Yes.
For example... When you take a clone, and apply a rooting product (typically salicylic acid like that found in aspen buds, willow branches, or aloe vera) you are using hormones to get a stem to produce roots. Another example, auxins are responsible for why plants curve their stem growth towards the light, and why roots curve their growth down into the soil; both are a response to the presence of auxins. Abscisic acid is responsible in catalyzing the mechanism for opening and closing of stomata.
Make informed decisions about what you use in your garden. Be smart about what you use on your plants and if you're not comfortable or unsure with something, then don't use it. Ultimately though... you need to be careful how you interpret what you read, and who the source is and what they're trying to achieve. Most of the studies that are done are with plants that have a great economical value, and the products they tend to use on those plants are things that we as organic gardeners can source from a natural form, they don't
need to be created in a lab. For example, Round Up is mainly auxins, (yes there are other things in it as well), but the auxins are concentrated so high they exhaust the plant by basically growing itself to death.
Keep on reading though. This is a great topic to understand if you like to grow basically anything
I am definitely not well informed, but I am still learning!