Calling a fact "absolute" doesn't make it more true.
To have some answer, often it's sufficient to mind how stuff works.
What's a prechamber diesel? Why was it invented?
It's obvious that diesel engines didn't born that way. They were single chamber engines at first.
The problem was that this kind of diesels worked well in big static application, or marine engines. When someone tried to do automotive diesels, the stuff proven to be too fragile.
Why?
Cause in a direct injection diesel, injection pressure and good timing is all. The more is the pressure and the more precise is the injection time, the more efficient, less mechanically stressed, and lighter is the engine.
But, back in the '20s, high pression pumps and injectors are heavy and costly things. Not compatible with automotive needs.
So, someone (yes, I know who) invented the prechamber diesel engine.
A prechamber injection system, is practically a two stage injection system.
First, when the piston is rising, and the pressure in the cylinder is realtively low, a low pressure injector injects the fuel in the prechamber. Then, since the prechamber wall is hot enough, the fuel begin to burn, and the pressure spike is enough to project the majority of the fuel in the main chamber, and obtaining a good air/fuel mix, when the pressure in the main chamber is enough to make it burn. First a mechanical injection, then a thermal one.
But there is nothing as a free lunch. In prechamber diesels the head has to be heavy. The larger surface area of the combustion chamber reduces the thermal efficiency. The ignition delay, from the mechanical injection to the combustion of the main part of the fuel, is bigger, so a big part of the fuel burn when the piston is lowering, thus lowering the eficiency of the engine (an engine can have a 22/1 geometrical compression ratio, but if the fuel burn when the piston is middle way down, the gasses are decompressed only two times, and therefore work too little). Moreover, since the engine is designed taking into account the combustion delay, a combustion delay had to be. If the conditions into the cylinder are too favorable to combustion, an so it's too rapid, for example because a turbocharger has heated the room too much, the result is destructive (in a direct injection engine the problem is less acute, since the fuel is injected at the time when you want it to burn).
This is the kind of drawbacks which manufacturers accepted until the '80s, according to you not to use solutions that were already there in the '30s, after which politicians snapped their fingers, and suddenly all the manufacturers have adapted to their desires.
Ok....
However, the problems that a direct injection gasoline engine has to solve, are different. In a gasoline engine, the injection timing, and consequently the pressure, is less important (infact, low pressure indirect injection engines work very well). In a gasoline engine you don't have to inject fuel at the exact time you want it to burn, since you send it in an environment such to make it spontaneously ignite. In a gasoline engine, at any time you inject the fuel, it will burn only with the spark.
But the DB601/605 example is intersting anyway. Since you talk as if developing it's direct injection system had been a walk in the park for DB technicians...
