Continuing the discussion from Proof of editing sources:
I don’t recall any disappeared non-spam topics. Do you remember what they were about? Maybe it got merged into another topic? Maybe the topic author deleted it themselves?
I generally only close/delete/hide posts if there are targeted attacks/hostility or any bigotries. Negative feedback (which does not include outright hostility etc.) is left as-is. I (and we/MeB) agree that negative feedback can be (and often is) useful.
I doubt that. The particular topic had several replies and it seems not possible for normal users to delete their own OP in such cases:
You don’t have permission to delete this topic. If you really want it to be deleted, submit a flag for moderator attention together with reasoning.
The first one was in German. A user complained that Picard had deleted their files(?).
(They were throwing a tantrum, swearing in the topic title etc. and, as you implied, it might’ve appeared hostile.)
I assume the files were just moved to an unexpected directory.
Later when I went to check on the topic once again I was no longer able to view it.
@outsidecontext might also remember that topic.
In the topic about cover art @yindesu mentioned OP was demanding something along the lines that editors should upload full scans when adding releases.
Quite a lot of people replied in defense of the MB community. E.g. that not everyone has the time and/or equipment to provide scans, some are hesitant to upload booklet pages consisting of copyrighted text only, etc.
If I remember correctly the original post was flagged at some time and since I know Discourse has self-moderation features I suspect it was automatically deleted.
People get worried when things are automatically deleted while no one seems to be looking.
It’s not this one?
I don’t remember the disappearing files topic, but given your description it’s likely I just ignored and forgot about it after initial replies 
But I remember the cover art Scans topic well. It was rather aggressively requesting everyone to provide scans, because the OP had cool scanning hardware that allowed them to scan entire booklets in seconds.
It definitely was not a nice topic, but I also don’t remember a real reason to remove it. As far as I remember it was a hefty argument, but not insulting or something. But I’m also not very thin-skinned in this regard, so others maybe saw this different.
No, it was a different one
There goes another one:
Related discussions:
That one said it had been temporarily locked due to a large number of flagged posts or somesuch when I last saw it a few hours ago.
@Freso closed it with some comment directing the relevant users to MetaBrainz contact page. I guess he completely hid the topic afterwards. As this escalated with insults, harassing of editors by private message and legal threats I’m more than happy to see it gone.
Yes not bad, but it did contain some true Golden quotes 
in there.
Something like:
I am a very famous celebrity, I know the handsome royal person but you, punks editing the cyberspace, you don’t know.
It disappeared because I hid/deleted the first post of the topic. It had several sockpuppet accounts in the topic itself and just a lot of personal insults and accusations, as @outsidecontext noted, and I also posted a note at the end to redirect the “prince” where to go if they wanted to escalate further.
Nothing automated going on here.
@Freso Maybe there is part of the issue: You posted a link to the last reply on this topic, but probably only you can see it. Everyone else (or at least every non-admin) sees the “Oops! That page doesn’t exist or is private.” message. So nobody can actually see why this was hidden, unless they happened to read this reply before you hid the entire post.
Maybe if there would be a way to have direct links to topics still work in cases like this would be better. Not sure if that’s possible with Discourse.
Oh, I see. 
Yeah, I don’t know if that’s possible. I thought direct links still worked.
Edit: Unhid the topic in question. Is it viewable by others now?
Nope, that link still shows “Oops!”
Okay, I think I’ve undeleted but unlisted it. So if I have it right the topic will not show up in the overview pages, but the direct link should work now. :x
Yes, I think this worked. Direct link is available, but the topic shows the crossed eye icon with a tooltip explaining that the topic is hidden and not visible in any overview. 
Another non-spam topic disappeared recently. It was flagged at least twice priorly.
