You don't really need to read all that. You'll find the meat of the whole issue before you even have to scroll down the page, when Ms. Hayden points out three things about such lawsuits. Her second point addresses something that comes up a lot in pop culture conversations:
“Non-writers think it’s the ideas, rather than the execution, that make a book. They’ve got that backward.”
I submit this as a Law of the Internet, on a par with Godwin's and Poe's: "Hayden's Second Law".
As I said, this comes up a lot. "Plagiarism", per se, is seldom invoked, but milder euphemisms abound: "derivative" is a popular epithet, and to many, "originality" seems the highest criterion for literary merit.
The career of the Gentleman from Avon indicates otherwise.
I should note that I'm guilty of this, myself; I've repeatedly tabled my own flailing attempts at writing because my characters, settings, or plot seem "derivative".
Addendum: just a few hours before I made this post,
foofers provided a technological example of "it's not the ideas, it's the execution" -- in this instance, whether the ideas got executed at all.