Recently I have noticed several of my comments end up deleted. I don't think my comments were unhelpful, spammy, or otherwise something that shouldn't be seen. In fact, I'm quite confident that the reason they aren't there anymore is because the are children in the reply tree to some comment that was deleted earlier up the chain (and it was that comment that was unhelpful or could otherwise be deemed inappropriate).
Here are two examples:
This comment was a reply to someone thanking me for making a video. The comment it was in reply to was also deleted. I suppose that comment didn't add anything to the discussion.
This comment was on why CF rounds need to have problems that are shorter to code compared to IOI. I think it was deleted because it was part of a blog written by Eva that was somehow deleted, which is apparently a running theme.
There are some other examples as well of similar nature.
Why/how is it happening?
Who is making these decisions, and on what criteria? To me it isn't obvious. Are there just some special users who have the ability to delete other people's stuff? Is that an IGM/LGM privilege that I just haven't earned yet? Is Mike manually deleting rows in some SQL database every time this happens?
Why subtree delete?
In lots of these cases, I remember interesting and valid things being said by myself and others that are no longer visible. Is it intentional to delete the entire subtree of comments rather than just the egregious one(s)? I suppose for the case of deleting blogs it may be a different story; I can imagine technical difficulties that would arise when trying to hide a blog, but not its comments. But what about comment subtrees?