With very few exceptions, all of us are dealing with damaged soils. They are depleted of nutrients and they have been damaged structurally through compaction and abuse. In some cases, precious topsoil has been removed and replaced with a substandard facsimile of soil during property development.
Gardeners should always be soil builders. We can learn a lot by observing how nature manages soil; no-till, top-down soil building. The effort we put into growing great soil will be returned many times in the health and beauty of our plants. There is nothing you can just pour on a plant that will compensate for bad soil. It all starts there.