SubhanAllah, I was asked this very question today & Allah gave me the answer.

The Ghayr Muqallideen argue that why should there be differences amongst the Imaams when the Qur'aan is one and Rasulullaah is one?
They claim that this merely confuses people.

In reply we say that the first addressees of the Qur'aan were the Sahabah y and
because they understood the Qur'aan and Ahadeeth directly from Rasulullaah (SAW), they are a criterion for us to follow. Despite the fact that the Qur'aan is one and
Rasulullaah (SAW) was one, there still existed many differences between the Sahabah (RA)

Since the Imaams were followers of the Sahabah (RA) and the Taabi’een, there
naturally arose differences amongst them as well.

With regard to the difference amongst the Sahabah (RA), Rasulullaah (SAW) said, “When I asked my Rabb about the disputes to arise between my Sahabah (RA) after me, he sent revelation to me saying, ‘O Muhammad! Your Sahabah (RA) are like stars. While all the stars are radiant, the radiance of some exceed the radiance of others. When their opinions differ concerning a matter, a person following the opinion of any of them will be rightly guided.” Rasulullaah (SAW) added, “My Sahabah y are like stars. You will be rightly guided by following any one of them.”1

Because these differences were based on sincerity, they cannot be condemned and are in fact a source of Allaah’s mercy, as Rasulullaah (RA) himself stated when he said, “the differences amongst my Ummah are a mercy.” Here Rasulullaah (SAW) was referring to the differences between the Sahabah (RA) and amongst the Imaams such differences were plenty. Shah Wali’ullaah Muhaddith Dehlawi mentioned that there were those Sahabah (RA) who recited Bismillaah audibly in salaah while others did not, those who recited the Qunoot in the Fajr salaah and those who did not, those who regarded vomiting and bleeding of the nose as factors nullifying salaah and those who did not, those who regarded touching a woman or the private part as factors nullifying salaah and those who did not, those who regarded eating roasted foods and camel meat as factors nullifying salaah and those who did not …”2


1 Mishkaatul Masaabeeh (Pg.554).
2 Hujjatullaahil Baaligha (Vol.1 Pg.376).