This is an opinion question, any answer can be right is explained well. i would say: no, elements that contributed to the novel were not included in the movie, as an example, the absent parents were mentioned a few times in the book and served as a good explanation for Ponyboys way of living with his brothers while the movie didn’t mention what happened to their parents at all.
Not all of them. They didn't show parts from the book that also were key to why the novel was so good. For example, when Randy visits Ponyboy at his house when he was hurt. This was a wholesome moment and it should've been in the movie as well.
