Why do 600 miillion Hindus bow down to statues? Cultural traditions hammered home with tribe mentality.
Some know it is wrong to commit wrong acts, they do not do them or go along with the crowd.
Intellect may eventually solve everything, human rights and laws in most countries testifies to trying to do what is best, but Divine Revelation makes it more certain to happen in shorter time.
I am reminded that the Greeks were great thinkers but had slaves and thought women were inferior and should not speak, at least they got one thing right with intellect!