The null hypothesis around here seems to be that HN mods are changing titles because they are title nazis. Instead what might be happening is the algorithim is

The null hypothesis around here seems to be that HN mods are changing titles because they are title nazis. Instead what might be happening is the algorithim is retitling the posts. Example: if 10 people submit the same link, only the first one creates a post and the others upvote that post. But what if the other 8 still count as title votes: say 8 of them use the same title, then the title in the first story auto-updates to use the common one (which of course is the actual post title). The net result and the whole point of all this would be to strip out anything added which includes both positive context and negative bias/editorializing.