Must everything have a spoiler warning?

From the wikipedia page for Reading Mastery 2:

Spoiler warning: Plot and/or ending details follow.

"The Pet Goat" is the story of a girl's pet goat which eats everything in its path. The girl's parents want to get rid of the goat, but she defends it. In the end, the goat becomes a hero when it butts a car robber into submission. A sample passage:

A girl got a pet goat. She liked to go running with her pet goat. She played with her goat in her house. She played with her goat in her yard. But the goat did some things that made the girl's dad mad. The goat ate things. He ate cans and he ate canes. He ate pans and he ate panes. He even ate capes and caps.

Talk about giving away the entire plot! Bastards.

For extra credit, tell why The Pet Goat (a Reading Mastery story) is culturally important enough to merit it's own wiki page.