This may be true. Perhaps living with the herd all the time made Ali more ready to submit to rules set by others. At least I have the impression of the Old One, the leader of Ali's herd, having a great degree of influence over all her followers. I don't know how much she would tolerate insubordination or questioning of her rules.
Then again, Ali does make up her mind to go adventuring with Littlefoot very quickly. She mentions her doubts, but is very ready to follow Littlefoot the moment he mentions Cera, Ducky, Petrie, and Spike (which may suggest that some kind of jealousy may have been an important motivation for Ali). We don't know if Ali was in any way punished for leaving the herd on her own accord, but I don't think so (we don't get the slightest hint in that direction). I guess we know just too little about Ali and her circumstances of life to draw many conclusions about her character.