What is the intended meaning of the narrations from 'Ali and Ibn Mas'ud regarding sequence in Wudu?

Primary text

When 'Ali and Ibn Mas'ud spoke about not minding the starting point, Ahmad interpreted this to mean specifically regarding the left versus the right limb, because their derivation from the Book of Allah is the same. Furthermore, a clear narration from 'Ali states that one should not start washing one part before another until it is as commanded by Allah, and the other narration attributed to Ibn Mas'ud is considered to have no established basis.