Facebook obviously didn't created those behaviors, as it didn't created voyeurism. But they cannot be exculpated from being a cause of voyeurism spreading out the way it is.
I mean sure, their success is huge, and lots of people would have a hard time living without FB. But if prostitution or heroine was legal, it also would have lots of success and (more)users. But would we be right to say it's a good thing ?
And yes, voyeurism is not heroine, but it's certainly not a good thing either.