The moderators bury things on the front page pretty routinely.

That's a pretty big (and vague!) accusation to just throw out there, especially in light of this comment elsewhere: https://news.ycombinator.com/item?id=13858327

dang 6 minutes ago

As others have pointed out, the [flagged] annotation means heavily flagged. A story can be downweighted off the front page by user flags long before [flagged] shows up. Indeed that's what happened to the submission the OP is complaining about. Moderators never saw it.