It's cool that this is such a hot topic still.
I didn't dig through all 10 pages but I'm surprised nobody is coming right out and saying it.
Why has it not been beaten? ...luck.
All pool games feature it, even game that is supposed to minimize it. Every break shot is a bit of a crapshoot because of the tiny gaps affecting how the racked balls spread. You can't totally predict or control it.
So there's potential for a funny roll leading to a tough shot (or no shot) after every break.
It's not a 50/50 coin flip, the player's skill tilts the odds in his favor. But even if he comes up with something makeable 90% of the time, after 37 racks, eventually those odds catch up and he'll have nothing worth shooting. Or he'll finally miss one of those 80% shots he's supposed to make, because after 15 or 20 of those, you're just due to miss one.
Maybe the table helped, certainly mosconi's skill helped, and the number of attempts, but at the end of the day, having something worth shooting after 37 break shots is a bit of a statistical miracle. That doesn't factor in all the other bad luck that works against you too like skids, balls tying back up despite a heroic breakout effort, etc.
I think Mosconi's run was the perfect storm of a guy with top tier skill, getting all the rolls, or at least no bad rolls for many hours.