There's a well-known MB salvage facility somewhere in Georgia - I think Atlanta. The fellow who runs it has torn apart a kazillion MB engines. In addition he holds a degree in chemistry. I cannot remember the name of this place, but have seen a discussion on the WEB back when that he participated in regarding the green vs. MB stuff.
His belief mirrors yours and mine. Pure bunk. The neck is made of plastic. Extremely corrosive chemicals, far more corrosive than any coolant are shipped in plastic containers far less durable than the plastic in an MB neck. He too said that it was overtightening that killed the necks.
I use MB coolant, more for overall internal protection; not because I fear the green stuff will break the upper radiator neck.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.