I don't understand why you are so fixated on having a form of punishment when it is not needed. I cannot come into your home and steal your computer, or whatever.

You also mention

You can establish community standards based entirely on opinions.

First of all, community opinions change quite drastically, sometimes year by year. Why should anyone have to be forced to abide to what a bunch of us think is correct behaviour.

I was always taught that you do not improve a situation through punishment, but through reward. We have a reward system and people have other natural needs, such as company, friends, admiration etc. Why impose flagging or downvoting, if it opens us to the possibility of someone abusing (abusing means someone was harmed) and we being forced to get together to express our disapproval - which will still leave the harmed person feeling traumatised.

Over the last two days I've seen how that works - some people just don't care if eveyone does not approve of them, they believe they have an inalienable right to do as they wish.