Because it’s fun, frequently free, and can be made by all.

It can be as simple as a well-placed rock on a stump
Or small stones perched on a hunk of granite.

Or a temple built with beach rocks.

That fun is just lying in the sand.
Opportunity abounds.

And for those higher ambitions:

Art is all around. Why not make some?
Because the world needs all the artists it can get.