Internet Comment Etiquette, does it exist?

So I stumble across a lot of comments/feedback on many post,even mine.And at times I think to myself "My goodness,even if the comment is true to the person who posted it... is it even necessary? Did the person even think about if what they posted was kind or not?"

I learn that not everything that is in my mind needs to be verbalized or typed out because even if it may be true to me. I actually think about the other person and whether or not if what I might comment is necessary or kind.Like the saying goes "Think before you speak." Now it should be "Think before you type." :D