At the danger of not knowing exactly what the conversation has been about ... not that this has ever stopped me before ... I'm not sure that I agree with that statement.
Different games, and different modes of play, are generally better at certain things. When you slather on adjectives like a kid with access to a jar of Nutella (rich, coherent, vibrant), it seems clear that this is supposed to be a statement that these narrative games are "as good" as D&D- a statement I completely agree with.
But they aren't "as good" at D&D at certain things- just as D&D isn't "as good" as those games at other things. If all games were equally as good at the same things, there wouldn't be a need for other games, and people wouldn't have preferences between them!
For example, ne of the advantages of a single point of fictional authority (such as the "DM") is that it can be more cohesive.
To me, this is just an odd statement unless I am misunderstanding it; these games are not D&D, and their strengths and weaknesses are different. They are as capable of producing a rich and vibrant session as D&D, definitely! But I prefer to celebrate their strengths in the sense that they are
different, not in the sense that they are the same.