Permit for two reasons. City will do a inspection to make sure you meet the code. City could increase you tax because of increase property value. You report to insurance , they may increase your rate but it would be covered by policy.
You deck is not too big not too high. Many people would built it without permit. Rarely heard any trouble. But if you do not build it to meet the code and someone is injured because of that. You have to take responsibility. If later you sell your house and inspection find the deck not meet the code, they may ask you to remove it.
So the point is building to the code.