You're mixing up section 230 with the situation prior to section 230. There were two important cases prior to its passage:
- Stratton Oakmont, Inc. v. Prodigy Services Co., in which Prodigy was found to be liable due to their content moderation, and
- Cubby, Inc. v. CompuServe Inc., in which CompuServe was held not liable for content, as they were unaware of it
Section 230 was in fact created to change this - to allow companies to moderate without making them liable for all of the actions of their users.