I think just the difference in the "mass" part of "mass-market."
I'm not talking exclusive to rich people Armani's here, I'm talking all the mass market luxury brands. Heck, even Nike's $200+ sneakers...
"they managed to do something that was previously unimaginable in business theory - create a mass-market luxury good."
Is not about that. It is about the (perceived) impossibility of a mass-market luxury good.
But "mass-market" is a term for broad appeal/sales (dictionary: "the market for goods that are produced in large quantities"), not for over-the-top revenues.
And as for that, more people have Nike shoes than have an iPhone. But even if 1/15 as many had, it would still a mass-market good, with luxury price / appeal.