This is kind of an amateurish article. It's like they said to the writer,
"hey prove that PG movies make more money than PG-13 movies." The only
way he could do it was by combining Rs and PG-13s together. PG-13s still make
more money than any other rating, and are kind of the default rating for films
these days. The PG films of today are much tamer than they were in the 1980s. I
remember watching straight PG films that had plenty of gore, swearing and even
nudity back in the day. Now days' PG-13 is about where PG was 25 years ago. PG
is where G was, and G must be really hard to get.
It's not just that you can't take kids. Another reason R-rated movies often fare
so poorly is that most of them attempt to use sex, violence, and profanity not
to tell a story but in place of one.