Agree; however, abuse on both sides will always be a risk. Copyright owners may very well start flagging campaigns against people posting videos that have concepts similar to existing or upcoming movie themes, etc, etc.
Killing an account does not stop serial offenders as we see this in other aspects of our society; however, we may deter their participation in the platform.
The blockchain is meant to be immutable (a concept I with which I agree) - in the same manner society knows that a wrongdoing by an individual cannot be undone.
This is very much a values issue - what does the Steemit and DTube community see as right and wrong. Every day members of the community get to vote democratically on all manner of posts, equally we have the opportunity to encourage a change in attitude/s for the better. This system provides a better option than many have with their own governments, be they democratic, socialist, communist or any other persuasion.
Flag them to zero and stop the post or video from being seen/accessed.