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.
Please note that, although there are scores of anecdotes in this thread, precisely none of them link to any examples or give enough details to find them. It’s always like this with Wikipedia detractors; I don’t know why, but it is. Complaints and horror stories galore, but nobody will link to any of it, preventing anybody from investigating what actually happened.
In the past, when I've tried to keep receipts on this sort of thing (which requires an extraordinary amount of effort, and is often only possible if you've anticipated that there would be a need to do so - since content is often deleted or archived without warning, and nobody ever enters an argument on the Internet with the expectation of talking about that specific argument years later) and actually presented evidence, I've been accused being "creepy" or various other forms of misconduct, and the argument is still not taken any more seriously. I've given up on presenting evidence of this sort of thing because the people who ask for it are not being intellectually honest, in my extensive experience. They don't care if you can actually prove what you're saying; they will ignore you anyway.
And even if, as you say, all the evidence has been completely deleted, an honest critique would at least point out the exact article in question, and summarize the details of the attempted changes.
But all the criticism in this thread (and elsewhere) always lack this. It is a mystery.