Nothing... But If you give someone a reason to come after you though don't be surprised how they found you.
I will give some more food for thought.. Your car is your prized possession that you care enough about to post all over the internet for everyone to see and know what you have and what is worth what. Now, why would you want to let the whole wide world know where you live or where the car can be found?
Just think, it's like putting a lock on a glass door. It stops the honest people.
Block your plate or not, if anyone wanted to find you... they will anyway so..
Why purchase a car? Someone may take it...or even worse, you can have an accident. Cover all bases now.