It’s a weed because it is an an invasive plant in many U.S. states due to its aggressive spread via seeds and rhizomes, which can form dense monocultures that outcompete native vegetation. It was introduced to the USA for erosion control. Only one state, Minnesota, classifies it as a “noxious weed.” Missouri, Wisconsin, North Carolina, and Michigan keep an eye on it but haven’t classified it as “noxious” yet.
I love the word “noxious.” It needs to be applied more often to Democrats.
Speaking of noxious and Minnesota, there’s Tim Walz.
Some farmers up in northern Nebraska used to plant it as a green manure as fixes nitrogen but its easier to fertilize then it is to plant it, take land out of use for a year & then have to disc it into the ground to get the benefit.