> What exactly provided great reach here? Is it the creator or something else.

Irrelevant, in the initial understanding of Section 230 that this thread was advocating for returning to. Only the author is responsible for the content in that framework, not the platforms distributing and/or promoting it.

In Section 230 platforms only maintain protection as a neutral party, anything getting promoted by them puts them at risk.

“letters to the editor” are a very old form of user generated content, but the act of selecting a letter and placing it in a prominent position isn’t a neutral act.

For clarity, they do maintain limited editorial discretion. Section 230(c)(2) states that service providers and users may not be held liable for voluntarily acting in good faith to restrict access to "obscene, lewd, lascivious, filthy, excessively violent, harassing, or otherwise objectionable" material.

Further, Section 230 contains statutory exceptions. This federal immunity generally will not apply to suits brought under federal criminal law, intellectual property law, any state law "consistent" with Section 230, certain privacy laws applicable to electronic communications, or certain federal and state laws relating to sex trafficking.