Coleus is a native tropical plant, so it's not surprising you found one growing wild. We in colder climates grow them as annuals or overwinter them by letting them go dormant, so it would take many, many years to get to the size yours is. No one in colder climates would have had things like you describe happen.

With your plant it would have optimal growing conditions. The stems are brittle so I can see them snapping under the weight. I can see them growing roots too, because they root so readily from cuttings.

There are other plants, especially nonflowering plants, that send out roots while still attached to the plant. Philidendron is one that comes to mind. It has little nubs of roots all along the vine. When these roots touch soil they root and start a new plant. Anything that grows then is the new plant and is cut off from the mother plant even if it is still attached. You can snip it off and move it then