Add to that, if the filly really has that nice of a pedigree, it seems improbable that the owners who could afford to produce her/buy her wouldn't have enough money to turn her out for a year and let her grow up rather than risk permanent and/or catastrophic damage by breeding her before she was fully mature. I'd call that protecting your investment.
I agree 100%, a 2yo filly is still growing and developing, you are pretty much asking her to continue to grow and finish off, while trying to produce enough energy for a living, growing foal inside of her. If they had the $100k to breed to Smarty Jones, I think they have the cash to let the filly grow up for a year.
