P.S. If you are " seeking the truth ", I would suggest asking the reals experts at The Tire Rack.
They are hardly "experts" at determining tire pressures for all cars, drivers, and driving conditions.
All tires are placarded for their maximum load capacity at maximum COLD inflation pressure, but since OEM tires are always selected to have considerable load margin, the maximum cold pressure placarded on the sidewall is rarely required.
Mercedes' tire pressure recommendations are very conservative, and more rear pressure is specified because at gross weight with rear passengers and the trunk loaded, the car will be rear heavy, but under typical load conditions of one or two people the car is front heavy. This is why running positive front tire pressure bias will improve handling, but Mercedes recommendations are conservative to ensure that the car will understeer excessively.
As I said, tire pressure is a tuning parameter and the only basic requirement is to maintain sufficient pressure to handle speed and load conditions, but higher tire pressures are optional as are different pressure biases to tune the car's handling to individual preference.
As a point of reference most lower speed rated tires are placarded at 35 or 36 psi maximum cold pressure. V and above speed rated tires are usually placarded at 44 psi, and some of the newest Z-rated tires are placarded at 51 psi, maximum cold pressure.