Not only that, another issue that no system of moderation at that scale will ever be fully consistent, and the more detail you give, the more people will pick at the subtle inconsistencies of the moderation. The classic "X did something similar and didn't get banned for it".

That's not what I mean by learning.

Most people aren't the nihilists you might expect them to be. Most people want discussion to lead somewhere new. That's why there is value in moderation: we use it to trim the patterns of discussion that lead nowhere.

So when a moderator deletes your comment because it was leading to nowhere, they can also tell you so. If they can teach you how you might lead your next discussion somewhere, then there is a good chance that you will do that next time. If they just quietly delete your comment, then that guarantees you will follow the same tired pattern next time, because you won't know any better. Rinse and repeat.

Of course, the nihilists (trolls) will still be there, but it's worth at least trying to teach people how to not be one.

fair enough. A reason is only useful for a person with good intension. But hey we are talking about the Internet here.