Mail on HabrHabr
From time to time, reading topics, I want to leave a comment for the author. For example, about a grammatical error, express your thoughts, suggestions, ask for an invite, suggest where you can get material for a more complete coverage of the topic. All these things are wiser to do with personal messages, which, unfortunately, are not implemented in the most successful way.
As you know, you can write messages only to your "friends", so you have to add almost all horrible. And if I basically do not want to have friends?
You have to make an application for adding to friends, and already indicate your ideas and ideas in it. Agree - uncomfortable? Why not refine your private messaging system? Then comments on topics will be much cleaner. ;)