Mercedes-Benz fell off after they gave a facelift to the W211 E-Class. They used to make some nice cars that would just work for a long time as long as you changed your fluids, but then they started complicating things too much and adding more parts to offset their engineering. Their frames were also made out of thick steel up until the late 2000s. As a kid, I remember one of my neighbors had a W210 E55 AMG. What a car that was. Lasted them for almost 20 years. I don't think a modern Mercedes will make it that far without electrical or powertrain issues because they've made them more complicated.
The question isn't how overbuilt a car is anymore, the question is how simple is the car. Too many components will lead to more lights popping up in your car, and eventually it won't be worth repairing the car given its resale value. That is where we're headed nowadays.