Something I just realized...
Hannah made everyone feel like they were to blame with her tapes. Not everyone deserved to feel that way, especially Clay. (Of course, some really did deserve it but this is to those that didn't.) They'll have to live with the grueling thought that they're to blame for her death forever. And that can take a serious toll on a person. She inflicted pain upon others with her tapes, and in turn, their lives crumbled down with the guilt. Maybe this purpose served as vengeance (plot twist?), the endgame of the show did not concentrate on building up what was broken. No lesson was learned, instead the people blamed were dragged with Hannah to live in their own personal hell.
But the real question is, did she have the intent of causing this mental pain on her classmates? Did she want them to continue their lives with the torture of regret, guilt, and self-hatred? Did she know that all of this pain can also in return, inflict depression or suicidal thoughts on others? If she did, then the story goes beyond the depths of darkness than we could ever imagine, and maybe Hannah is not who we think she is (theory), but there is more to this story than people are realizing, and what we see only covers the surface.