Seems your guide has made my argument.
"we don't need the extra capacity now, so they turn them off to save mechanical wear on the turbine".
So they build these complex and expensive machines, and yet they still rely upon the old technology unless it's a peak load situation. That's completely ass-backwards from what it should be.
It's another example of how deploying windmills and solar is a waste until we have a storage technology to accommodate them.