It's because it gets the most plausible answer, even if it's only a small chance of being correct. If there are not that many words, there are only a few object

It's because it gets the most plausible answer, even if it's only a small chance of being correct. If there are not that many words, there are only a few objects that could be draw with a L shape like that. I mean, even if you draw something else starting with a L shape, it will probably be a slight different L shape (with a curve, for example). I think that's it, doesn't really mean it's overfitting, it would mean that if the probability was really high.