Quranites don't read the Quran! Look at this verse in the chapter of the Women [4:65]
"But no, by the Lord, they can have no (real) Faith, until they make thee judge in all disputes between them, and find in their souls no resistance against Thy decisions, but accept them with the fullest conviction."
The first part says they do not believe unless they accept his judgement, whose judgement? The Messenger of Allah (peace and blessings of Allah be upon him) that's who.
This meant initally the people of Mecca who had to accept his judgement and this for us means following the hadith. How else are you are going to follow his judgements if you are not going to follow what he said?
Ponder the first part they do not believe unless - so this part is important because their faith means nothing unless they accept him.
In fact the definition of disbelief is to reject anything that the Messenger of Allah (peace and blessings of Allah be upon him) came with - with a condition that it is clearly defined by
mass transmitted proofs.
I feel sorry for the Quranites because they do not know they do not believe by the actual text they claim to follow!!
Also note that when Aisha (may Allah be pleased with her) was asked what was the Messenger of God (peace and blessings of Allah be upon him) like? She said he character was like the Quran. No one else was described like this!
About obeying the Prophet (peace and blessings of Allah be upon him)