I remember looking at the vote history where they decided The Greyzone (one of whose journalists was called to testify at the UN on their investigative journalism) wasn’t a “credible source”, the very first vote I checked belonged to a unique username that was used on other sites for an anti-Palestinian think tank academic.
For completely uncontroversial topics it’s fine, for everything else you have to read all the dismissed/shut out outsiders complaining on the talk page to get any real sense of the topic.
Wikipedia has little legitimacy which is the purpose of an encyclopedia, I’ll never donate $1 to it and if it shut down tomorrow I wouldn’t care.
A UN committee is equipped to go beyond simply reciting what secondary sources say. It can conduct it's own research, and carefully compare different secondary sources. So it makes sense for them to want to hear from people that sometimes say interesting things but aren't always reliable.
I don’t know what “employees of the Russian government” you’re talking about (maybe RT articles?) but I’ve watched WaPo and NYT perpetually without criticism or follow up publish White House and State Dept. talking points.