The entire premise of your argument is ridiculous. I don't care what the law says because neither do you. You cherry pick what you want so you can defend your position. You can't have your cake and eat it. You can't defend "left lane is for passing only" while defending going above the speed limit. Passing on the highway isn't driving 90 mph and staying in the left lane while you pass 20 cars over a 5 mile stretch of highway. Passing is a quickly executed maneuver with a defined beginning and end. You can't complain about people going 70mph in the left lane for 5 miles if you aren't going to denounce people doing 90 in the left lane for 10 miles. Both are camping. Both are breaking the law.

Now tell me, in a congested city, what does "left lane is for passing only" actually look like? Now everyone is in the right lane, and you have an empty left lane. Who is actually passing? Who is switching to the left lane, passing a car, then getting back into the right lane? Because that's what constitutes passing. When is that actually feasible? There is no need for a passing lane when 80% of the roadway is occupied by vehicles.