I have also seen in some documentary that there is another geoglyph out by the ocean that points straight for Nazca Plateau, any truth to this? And why would this be made in the first place? Also for dancing?
And to ask your question which i underlined in your quote; I know they got bored, I know they had fun, the question is would they take the time to design, execute and then dance around these lines? I don't know, but I would at least like some evidence supporting this, just like I would want evidence for the UFO related theories.
I put forward the idea of dancing, which I did see explained in a documentary years ago, because it makes as much sense as any of the other suggestions mooted here. The truth is we can only guess. Were all of these enigmas created at the same time by like-minded people? It's doubtful.
As for the flat plateau.....these are natural.