I am not sure if you have noticed but you seldom see trolls around steemit. The reason being that once they are identified they usually get downvoted/flagged to oblivion by the community and their posts or comments become less visible.
You also need to consider that all posts and comments are recorded in the blockchain (which no one owns). Once there, nothing can be deleted. It might not be visible in the website but you can see them using other tools or interfaces.
So once a piece of data is recorded in the blockchain it becomes inmutable and is recorded for posterity (unless if you are referring to Ethereum ;)
Your observation that there are not trolls on steemit is not valid. Is my actions step by step will be in the logs, sure! Each action has been recorded. But that is not what is in question here! Suppose I create a story or submit a story. Then, a troll come along and makes a nonsense comment spoofing the story. I can just delete the entire story and post again. Not very practicable but effective. However, trolls do not give up that easy! They have nothing to do and they like to hang around obstructing the post! People do not feel very motivated to comment or participate in a post that has been trolled. Have the ability to remove the troll is a right that must be given to the post owner.
I never said that there aren't any trolls in Steemit. I said that you seldom find trolls which is not the same. What you are asking for cannot be done on a blockchain as there is no central point of control (that's what makes it censor resistent). If you could do that then it would not be a blockchain it would just a be centralized database.
Some people here are confused between "freedom of expression", censorship, a story, a comment and an "offense" or a "disrespect."
So, the question here is: - When something is freedom of expression and when it becomes an offense, a disrespect?
When you censorship, you do not censorship comments. Censorship are for posts and stories. Comments are for moderation. It always has been like that and it always going to be. Some people just did not wake up to this fact yet.
If I say to you; "Go to hell with some MF words!" Is that freedom of expression or disrespect? Some would say; Yes, that is freedom of expression! However, there is a fine line between freedom of expression and an offense! By the way, that was an offense and not a freedom of expression!
If someone spoof on a friendly post; - Is that freedom of expression or disrespect?
When someone trolls a friendly post; - Is that freedom of expression or disrespect?
You see, some of you never been "Moderators" and therefore do not have the experience to talk about that, accordingly to what I read here, at least.
If you care to stop for a minute and think, most of you here are not even real! I am not talking to a real person, I am talking to a screen name! Is not that this really matters to a certain point, but when a person (that is not real) start to offend, spoof or troll others, then, that start to matter!
A person doesn't get anywhere by disrespecting and offending people and that is not freedom of expression. Some people might not agree with a person, but one will lose the argument when they start to disrespect a person for any reason. ... and there where moderation takes place.
A person that post or submit a story, must be the moderator of his own story. It is his/her story, not mine, not yours to disrespect, to spoof or to troll.