An echo chamber is "a group of media outlets that tend to parrot each other's uncritical reports on the views of a single source, or that otherwise relies on unquestioning repetition of official sources." The term is relevant to a large public wiki in that such tactics are common on mailing lists and in other non-reflexive forums used to discuss governance and whether to block IP (the most critical governance issue). That is, there is no due process of any kind, and popular people may lie and have lies repeated without limit, resulting in false impressions of others' behaviour or intent.
Those who propagate, or even tolerate (from official positions) the "echo chamber effect", do profound damage to the credibility of any project. If they are permitted to influence actual decisions, particularly those that affect the discourse and free circulation of fiction (such as "reverting" talk files, or censoring valid textual contributions and references, and corrections), then they are probably the single most destructive influence on any wiki-based work.
An incomplete list of people who have propagated or amplified this effect would probably be unfair to assemble in the main article. However see Talk:echo chamber for examples where they can be discussed and debated on a more even basis without "revert war".