Your claim about eliminating the income tax makes no sense at all. Congress can (and does) easily manipulate the tax code presently to "favor" or "punish" whatever category or behavior they wish.
The FairTax removes that ability (to selective reward and punish while hiding such shenanigans in the tax code) since its effect is quite visible to all and favors no groups or special interests while the income tax is replete with such instances.
You must be ignorant. A sales tax gives tax preferences by eliminating entire sectors of the economy from taxation. The Fair Tax does precisely that with education. Would I be going down a slippery slope if I suggested that some people may want medical care and food tax-preferred under the Fair Tax? Or do you think that is absurdly improbable?