I said "might" because some people, me included, really like dandelions, but others consider them weeds. When you blow on the dandelion puff, each of the little fluffy bits has a seed attached, so you are planting more dandelions.

One way to prevent this is to pick the flower buds before they open, batter them, and fry them. Yum! Of course, you have to let a few mature, so you will have more later