Earlier quoted context omitted.
What's actually horrible is committing acts of extrajudicial violence.
That's up to the thief to decide. It's pretty easy to avoid such "extrajudicial violence," simply by respecting the property rights of others.
There are a million things that can and often do go wrong already with our criminal justice system, but it does function, more or less, as a way of arriving at a just conclusion; your suggestion that we throw all of that out is, literally, barbaric.
I can't believe I have to say this, but society is worse off without laws and a just mechanism by which to enforce them.