The Center for Democracy & Technology posted a good overview of the complex interplay between Section 230 of the Communications Decency Act and competition policy. However, it is important to keep in mind that if Section 230 were changed in a way that incentivized companies to implement more robust editing policies, that would also change incentives for content creators. After all, if a certain category of content is less likely to make it through the various filtering technologies used by the big social media and tech companies, then over time, the economic incentives of creating such content will naturally diminish.
For this reason, I would caution against concluding—especially without having a specific policy proposal to analyze—that changes to Section 230 will inevitably help large technology companies and harm smaller, less well-resourced startups. Such concerns should be taken seriously. But the best way to undertake a serious, nuanced analysis is to carefully identify all of the new incentives that a new, specific policy amendment could create for the social media ecosystem.