Good grief OP.
Firstly, what people post on MN and how they are actually going to behave IRL are not necessarily the same thing. If they were, then locksmiths would be making a fortune and there would be an enormous tribe of bewildered DPs roaming aimlessly together with their possessions in a black bag because they left a cup on the side/slept in late/farted/wore the wrong clothes etc etc.
On a more serious note, by your logic, then MN should be contacting the police about everyone who posts about being the victim of abuse - because they are describing an offence right? I don't even want to think about the potential repercussions of that.
OK, so let's suspend disbelief and imagine that MN could somehow track us all down to our homes:
Scenario 1 - "Hello MN poster, we have been told that you don't actually agree with the latest Covid regulations and are going to have more than 6 people for a first birthday party, is this true?"
"Of course not officer (tinkly little laugh) I was just letting off a bit of steam and invented a vaguely innocuous scenario to initiate an informed discussion around the issue"
Scenario 2: Hello MN poster, we understand that your partner has been abusing you for a number of years and we believe that you are a victim of co-ercive control. May we speak to your OH please as this is a crime and we would like to charge him"
The fallout from this just doesn't bear thinking about.