Its basic hydraulics, every substance on earth flows the path of least resistance. Since both the radiator and block would be unobstructed by the t-stat, water would be flowing through both. But, cooling performance is significantly reduced since some hot water will always be recirculating back. If you want the most heat removal capacity on hot days, the best option is an unmolested and properly functioning thermostat.
Read the attachments. If Mercedes says its a bad idea, its probably a good idea to believe them since their R&D budget is a wee bit bigger than any of ours.
