> The REASON 230 was needed is precisely because without 230, if they control what's said and what isn't, they become liable. You're replying to someone who correctly stayed the common law. You're right that 230 provides an exception to the common law.
Even that is not necessarily true. Prior to the enactment of the Communication Decency Act, there were all of two court cases considering this issue. Cubby v. CompuServe said web services were considered distributors for purposes of third-party liability, while Oakmont v. Prodigy said that Prodigy's moderation made it a publisher. Neither cases were appealed, and thus neither set any binding precedent. The general consensus at the time was that websites should be considered distributors, and shock about how bad of a ruling Oakmont v. Prodigy was largely drove the enactment of section 230. That consensus could have been determined to be wrong (just like we were sort-of wrong about API's not being copyrightable for 50 years, although their use was determined to almost always be fair use, which is close enough for practical purposes), but we never found out.
Elaborating on that, the political talking points go on and on about how you are either a publisher or platform, when in fact, the law and precedent outside of section 230 recognize three groups - publishers, distributors, and platforms. Publishers (like newspapers) are responsible for what they publish, platforms (like telephone company) are not responsible for what their users do on them, while distributors are only liable for third party content after they have been formally notified of it's illegality. Traditional distributors, like bookstores (or any establishment with bathroom graffiti) are completely free to curate, moderate and censor however they wish and doing so does not cause them to take on the liability of a publisher.
I'm glad that Section 230 went a step further and declared web services platforms and not distributors, otherwise all the abuse we see regarding DCMA take-down notices would have also been occurring with libel and other laws, but I'm pretty skeptical that Oakmont v. Prodigy would have been upheld.