The Model 3 was a completely different market segment from the Model S, so they could hype the Model 3 to the moon without impacting Model S orders (atleast for a time).
With the Model Y, they can't brag how much better it is than the Model 3 because it will cause prospective Model 3 buyers to wait for the Model Y, rather than buying a Model 3 and Tesla needs Model 3 cash flow to fund the Y program.
The Model 3 was a completely different market segment from the Model S, so they could hype the Model 3 to the moon without impacting Model S orders (atleast for a time).
With the Model Y, they can't brag how much better it is than the Model 3 because it will cause prospective Model 3 buyers to wait for the Model Y, rather than buying a Model 3 and Tesla needs Model 3 cash flow to fund the Y program.