I don't think AMD or NVidia want to be blacklisted in WebGL implementations because their driver isn't secure enough. Only one or the other could get blacklist

I don't think AMD or NVidia want to be blacklisted in WebGL implementations because their driver isn't secure enough. Only one or the other could get blacklisted. If it was both of them, what remains? The Sandy Bridge GPU? WebGL needs them more than they need WebGL.