Can't say i agree.
Also an M rating just means that it isn't targeted towards children.
No. An M-rating means it contains content that is harmful for children or is seen as such in society. Games with different rating can be targeted at adults but don't include violence, sex, whatever, but still aren't interesting or even not appropriate for children.
For instance in movies, take movies with G-rating in the US (G means general audience and is defined by the MPAA as "All ages admitted. Nothing that would offend parents for viewing by children."). Among G-rated movies you find 2001: A Space Odyssey, Gone with the Wind or Planet of the Apes. None of these movies is intended for children.