There are times where the game could fall into a repetitive cycle of positions; especially goats may use this resort to defend themselves from being captured. In order to avoid this kind of situation, that rule was established.
As it stands now, a tiger player cannot move a tiger to it's previous spot from several turns prior, including capturing over the same space. Which means that even if the goat player loses a goat, they can put a goat back in the same space and it'll now be safe (vs. the tiger that just captured it at least). I'm not convinced it is possible to win against a competent goat player.