Aw come on, maybe your engineering degree is in a different field, but it isn't too hard to find out that for an internal combustion engine to run, the fuel to air ratio has to be within a certain range. That's why all engines have some way of metering the fuel in relation to the amount of air going in. So if it is running,it is getting enough fuel, and if it is getting enough fuel it is getting enough oil (assuming you did put it in the gas, right?).
Back to the question of timing vs throttle, interesting that you mentioned Martin outboards. The Martin "75" had a linkage whereby you could close the carburetor's throttle plate by pushing a button on the tiller handle, without retarding the spark lever, and the RPM would come down to sort of an idle. I say sort of because the idle was rough when running like that. To get it down to a nice smooth idle, you had to retard the spark. Virtually all outboards used in racing applications used the same sort of speed control. Who cares if a racing engine idles smoothly? And the Martin wasn't the only stock engine to do it either. On an early Johnson QD, you could slow down by raising the tiller handle. Various Evinrudes and Eltos had a small knob on the tiller handle. Lots of antique outboards had no carburetor throttle at all.
And I repeat, any 4-stroke bigger than a lawn mower has some sort of variable spark advance/retard. After they took the levers off the steering wheel, they put the automatic advance mechanism in the distributor, and it stayed there forever. Well at least till they started putting it in a computer in more recent years.
I also repeat, a two-stroke has an entirely different way of getting the fuel-air charge into the cylinders than a four-stroke does. So you can't be making direct comparison. A two-stroke can't run with the air supply strangled down like a four-stroke can. A Diesel always has the air supply totally unrestricted, even at idle. I know you asked "Why?" The short story is these things evolved over many years, and much was learned as they went along. Goal being an engine that runs well, is efficient, and trouble-free. And they are still working on it.