How about, the ones who care enough to put contact info in their profiles, you can reach out to them and say "you may not have noticed but the HN admins seem to have banned you".
I have sent dozens of those emails over the years. It's only a small fraction of the [dead] productive comments I find, but not that many people have contact info or googleable usernames.
How about, the ones who care enough to put contact info in their profiles, you can reach out to them and say "you may not have noticed but the HN admins seem to have banned you".