Did you know that Kudzu was brought into the USA by European farmers because it was so much cheaper, and easier, to grow than alfalfa? They specifically brought it to be food for cattle because it could grow anywhere no matter how bad the soil was. And that was the whole point. It provided a huge amount of protein to the cattle. Of course, over time, they abandoned their growings for alfalfa because of a large marketing campaign and the fact that alfalfa was easier to harvest and bale in neat rows than kudzu was, and handled colder weather better than kudzu does, and can be grown much further north. So that is why it is spreading the way it is down south. Humans brought it there and then ditched it to let it spread. Same with dandelions. They were brought to the Americas by Europeans originally as food crops and as medicine. It was insanely valuable to the Europeans and they would rip out the grasses, which they thought of as useless, to have crops of dandelions. It wasn't until the Aristocracy started showing off huge, fallow, useless spreads of inedible grasses, a show of power and wealth - look I can leave my land to go to waste and let it go fallow with no food growing on it, did you start seeing the rise of the "plain green grass lawns". As more and more people with money had such around their homes, it became a trend, a way to show you had status. And the humble dandelion, along with glover and other useful food plants, became a "blight" on those "perfect lawns" because they showed something other than beautiful green, useless, expanse. And that's how the dandelion went from food, to being thought of as a weed. Oh, btw, tiny thing, the humble dandelion helped save the Alliance forces during WWII, too. Russia used the Russian Dandelion, the most common type, and harvested the white sap from it to make rubber. Since the sap of the dandelion has the same makeup, or rather similar makeup, to the natural rubbers found in rubber trees.