The audience of a book does not restrain its abilities to make the reader question life, its meaning, and beyond. A book has the power to make its readers think about what could be in the big picture. A novel written for young adults shouldn't be ruled amateur or mindless simply because of its base of readers.
For instance, the Hunger Games trilogy had everyone talking about such oppressive societies, what courage really means, and the like. The trilogy happens to be considered young adult fiction.
It is perfectly possible for good quality young adult fiction to be thought provoking. There are some excellent novels for teenage readers that can be enjoyed by adults too and nowadays they are written on some relevant and interesting subjects. Some adult novels can be utter trash and more and more adults are now reading youth fiction which shows that the quality has improved and that there is something to hold the attention of the older and more experienced reader.
Unfortunately, I think just about any fiction can be thought-provoking, let alone fiction that is designed for young adults. Young people are clearly much more influenced then their respected older adults, so I do think they could possibly get some negative ideas in their heads from reading strong and powerful fiction.
I think it is entirely possible for young adult fiction to be thought-provoking. The only reason it wouldn't be thought-provoking is if the author chose not to include anything insightful or interesting in the story. Lord of the Rings was one of my favorite book stories growing up and I thought it had a lot of good lessons and morals within the storylines.