Supposing one of the scientist social networks implemented the refereed peer review process for some or all papers they host, funding it with ad revenue, APCs,

Supposing one of the scientist social networks implemented the refereed peer review process for some or all papers they host, funding it with ad revenue, APCs, and/or freemium instead of charging universities and readers, what more could they do to improve the system? Better post-publication review/redaction/amnendment for work we don’t realize is wrong until much later? A rating system?