No. Because the very basic understanding includes the ability to write phonemic transcriptions and understanding that ля is ль+а, and лья is ль+й+а, and that saying лъя or лья instead of ля is a mistake. And also there are much fewer combinations as лья in Russian than like ля.
How do you think: is п-б distinction important in Russian? The difference between л, ль is more important than п-б, because there are no weak positions for л – ль and there are plenty for п – б.
How can you prove that L – R distinction in English is more important than л – ль or т –ть in Russian?