Weeds grow where there is a biological niche for them in an environment. Sure, plants can be magical, but I don't think that weeds distribute themselves according who what some human who lives there needs. That is an awfully humanocentric world view, which does not take into account the fact that other forms of life do not live thier lives in accordance to human wants or needs.
Weeds are successful plants that are unwanted by humans. They are "misplaced, " in that they exist in places where humans do not want them. However, they fill necessary biological niches in the ecosphere, and perform various vital functions therein.