No, because it still isn't legal tender, and lacks credibility as a medium of exchange. The simplest example of this is loyalty programs that offer 'points' that can be redeemed for goods and services. Since the points are useless on their own, the vendor creates agreements with other businesses so that they accept the points.
That's what gives the rewards program credibility. Real currency still changes hands in the background, but the customer only spends 'points'. Currencies, although unbacked by gold, are still credible because they are legal tender and widely accepted in ways that rewards points are not.
Amazon and other private businesses can refuse to accept BTC whenever they want. Earlier this year, Tesla 'accepted BTC for payments', and then changed their mind a month later.