I have observed that many topics definitely not violating rules are disappearing from Codeforces. Examples of that are:
1) yesterday's blog with discussion about programming environments and editors (I couldn't even read two replies to my comments which were posted after I fell asleep, because at morning topic was already not existing),
2) "copy" of http://mirror.codeforces.com/blog/entry/23612 which I found pretty funny,
3) topic with my comment with >800 upvotes ;__;.
These are just few of them which came to my mind, but that happens definitely too often. What is the reason behind it? Are they disappearing because of nasty CF moderators which simply didn't like them? Or is it because their authors decided to delete them (more likely than previous one :P)? If that is the second case then I think that authors should not be given option to delete their blog entry. Option to change their post (already existing option) sounds much more reasonable and completely sufficient if author wants his post to be no longer visible. When deleting blog entry they delete not only their entry, but also whole discussion which is often much more valuable than entry itself thus deleting input from community and at the same moment cutting vivid discussion.