Well AMD are sort of the reason its becoming the standard. They kept pushing them to do it and took it as a marketing product to say we support it and etc.
Atleast its not closed off. Nvidia should just play along and support it as well. Tbh they could use it in their cheaper cards thus marketing G-sync as a 'high end' product. Then we'd end up in massive discussions about what is better but hey, I like choice.