>As a moderator, I will sometimes send a message to a poster whose post is removed. However, if it is "commercial spam," I don't bother because we both know why.
Sometimes redditors comment without understanding that they broke the rules. Sometimes redditors comment using spam and they fully know what they are doing. In the first case, a message to them to tell them why is helpful. In the second case, it's not.
I personally (as an active Reddit user), feel that the interaction with the mods there is always in a negative context. On /r/technology, for example, you can get ban without any specific reason and messaging the mods won't do anything.
A few weeks ago I made a silly comment in HN on a post that reached the front page. My comment got a few downvotes and one of the mods sent me a message with what I did wrong.
I then went one step back, understood that I wrote something that is against the rules of HN and sent the mod an email with an apologie. He replied almost instantly.
That's one of the reasons I prefer HN over Reddit. It seems like the mods are not here to punish, but to create a healthy conversation infrastructure and to lead users who are not into the HN spirit yet, into the right path