What makes something a weed? Interestingly enough there is no botanical definition for a weed. Instead, it is a term that is generally used to describe any plant that is growing where it is unwanted. Usually the plant is growing in a human controlled setting, is fairly aggressive, and is a nuisance. Just about anyone who has a lawn or garden has identified one or more plants as weeds, even if they did not know any other name for them. And there are some plants, like dandelions, that are almost universally identified as being a weed.
Yet I see nurseries selling pots of Grape Hyacinths. And obviously many unsuspecting people must buy them and plant them in their gardens. To me, that is akin to picking a dandelion seed pod and gently blowing it out over your lawn. I even had friends think they were doing me a favor by bringing me a pot of them as a gift. Pretty sure they got thrown away.