Why is the 6BT 12 Valve Considered the best of all diesels?

From Jalopnik.com:

“The most reliable, simplest, as basic-as-it gets, fully-mechanical diesel engine” a diesel tuner could ever ask for; in fact, the vehicle literally only needed a couple wires to turn the motor over with a starter; and once it was running, the engine needed no electronics at all. Compare that to the bag of snakes all modern engines have under hood, and you realize just how simple this motor is.”

Tyler from Diesel Power Products, a Washington-based Diesel performance parts supplier, and he said the basic formula for why the Cummins 12-valve is such a beast, saying it’s just “too dumb to die.” And that mechanical fuel injection system, he says, is the key to what truly makes the 12-valve “dumb” (but in a good way). “There’s even more Cummins 12-valve owners can do to add power besides fiddling with the P-Pump. With a different intake and exhaust, bigger turbos, a better lift pump, bigger injectors, perhaps a beefier crankshaft damper, new valve springs and pushrods, some basic head tweaks, and maybe a girdle at the base of the block to prevent crank wrap, many of the stock internals can handle 1,000 horsepower without issue.” “Unlike the later 24-valve ISB model that came around in mid-1998—which used a Bosch VP44 electronic rotary style pump—the 12-valve offered between 1989 and 1998 used a fully mechanical fuel injection system that used the cam to time when fuel was injected into the cylinders.”