Why did the MPAA introduce the PG-13 rating?

The PG-13 rating was introduced by the MPAA as a way to describe a movie as having a higher degree of intensity. The PG-13 rating stands for Parental Guidance for ages 13 and under.


https://www.history.com/this-day-in-history/pg-13-rating-debuts

Basically, from the introduction of the MPAA ratings system, there were issues about how to designate pictures that weren't unacceptable for children but weren't Disneyesque fantasies, either. The original rating system in 1968 was designated as GMRX, with M standing for "mature" audiences. But producers thought that that implied children shouldn't attend, so in less than two years, M was replaced by GP ("general audiences, parental guidance suggested"). But then that was seen as not being enough of a warning, so in about two more years (1972) it was replaced by "PG" ("parental guidance suggested").

Over the next decade, studios found out that there was a real market for PG films that were bordering on R ("restricted -- under 17 not admitted without parent or guardian"), and a lot of movies were targeted at that "hard PG" market. One of the most prominent filmmakers to do it was Stephen Spielberg, and the huge success of two movies he made in 1984 -- "Indiana Jones & the Temple of Doom" (director) and "Gremlins" (producer) -- created a real drive for an intermediate rating between PG and R; even Spielberg (in the linked Time article) said that there were parts of the Indiana Jones movie that he wouldn't want a 10-year-old to see. And so a new rating between PG and R was created: PG-13 ("parents strongly cautioned - some material may be inappropriate for children under 13"). However, unlike R, PG-13 didn't require an age check at the door; it was just a warning that the movie contained material that might not be suitable for pre-teens. And that is still the rating system in effect today.

https://web.archive.org/web/20101029133825/http://www.time.com/time/magazine/article/0,9171,926639,00.html
https://en.wikipedia.org/wiki/Motion_Picture_Association_film_rating_system#Addition_of_the_PG-13_rating

Edit: typos