Also, the original title of this thread was about a thousand times more informative.
Edit: I'm tempted to write a bot that will catch title changes and post the original title as a comment in the thread automatically.
Though, I'd be in favor of you trying and seeing the result. My test was limited and short lived so it may not be indicative of the full community.
As for how this happens, I don't know? Is this a from moderators import title_checking ... But then Arc is more functional so maybe it is done in code?
I'm still sympathetic to the title-change complaints, and I think HN is leaving a source of creativity on the table to the community's detriment. But the guidelines are theirs to setup and enforce.