I'm very late to this, but I wanted to say that partly the fault is on the naive assumption that search engines adopted many years ago that the information found online was mostly true if it had a lot of backlinks.

That's no longer true. If Google or Facebook don't want to censor content, then they need to change the UI and warn that some of the results contain wrong/misleading information, or even complete lies.

This fact-checking wasn't needed long ago because the pages with the most backlinks had almost always factual content.