How about I look at some of those cases? Especially if it's relatively recent, I can take a look. Leave me a message here, or at my email address (see my HN info) , or on https://en.wikipedia.org/wiki/User_talk:Kim_Bruning
I'm not very active anymore, but I'll check in the next couple of days and see what I can do. Really to be able to help I generally need links to revisions, but if you have a username, a page, and a reasonably short time frame (a concrete date) I might be able to figure out the relevant revisions from there.
To onlookers: When I investigate cases like this, there's often a "catch." Sometimes contributors really did break Wikipedia policies — and just don’t mention that part when telling their side of the story.
Now I'm certainly not saying every case is like that, so I will look, and if you don't get what the issue was, I'll try to explain. In some cases if it was recent and it somehow wasn't fair, I might even be able to'fix' it within the bounds of Wikipedia policy.
Are you familiar with what Larry Sanger himself had to say about the bias that has emerged in Wikipedia (https://unherd.com/newsroom/wikipedia-co-founder-i-no-longer...)?
e: another comment elsewhere on this post brought up another source: https://www.tracingwoodgrains.com/p/reliable-sources-how-wik... . I've read a bit of it and can generally endorse what's being said there. In particular, some specific usernames are cited and I recognize most of them, which in itself is telling. Other comments here suggested that Sanger's personal views are less than scientific, to say the least. I have not looked into this personally, but I don't think this in any way negates the argument about bias. (Nor is any political camp immune to pseudoscience.)
Also note that the issue is biases in there whole generality. Most data produced by the universe will just not attract interest of most human beings. Or at least, as finite beings, we have to pounder where we put our attention and can’t afford to study every single topic with the same level of scrutiny.