[JackC]

Just in general, the difference between having an editorial gatekeeper, and not, is that it gives the site operator actual knowledge of what's being posted. An example of how that would matter is the DMCA safe harbor, 17 U.S.C. 512(c)(1)(A), which requires the service provider not to be aware of facts or circumstances from which infringing activity is apparent.[1] But "how much did you know, when?" is a crucial question basically any time we hold someone responsible for something under the law, so "we knew exactly what was being posted to our site the whole time" is pretty different from "we couldn't possibly keep track of everything that was being posted to our site."

[1] https://images.chillingeffects.org/512.html