The reasons could be many. But the main reason is underdeveloped gluten. Such parotha will be challenging to roll paper thin. Instead, they will tear apart when stretched until paper thin. When we stretch such dough, the folds or layers stick back in the dough and do not separate. Secondly, you must be generous with oil while shaping layered paratha/Parotta. Fat helps the layers stay separate and open up later, crushing. It gets me to the third reason. It is not opening the layers when the parotha is still hot. Layers open up best when the parotha is still hot.