Why are some models better than others today if everything is publicly known and many organisations have access to massive resources?
Somebody has to come up with an idea first. Before they share it, it is not publicly known. Ilya has previously come up with plenty of productive ideas. I don't think it's a stretch to think that he has some IP that is not publicly known.
Even seemingly simple things like how you shuffle your training set, how you augment it, the specific architecture of the model, etc, have dramatic effects on the outcome.