Does anyone say Mbappe is in the conversation for the greatest of all time?
No, because when that conversation happens Ronaldo and Messi still loom over it, with Pelé and Maradona there as well, and nobody would try and justify Mbappé being in there.
However (and this is what matters) - the hype machine that increasingly absorbs this sport like the Borg uses stars for its fuel, and thus presents Mbappé or Vinicius Jr. in the MAXIMUM POSSIBLE WAY, a way modelled on the Ronaldo-Messi presentation over the last decade and a half. And it feels hollow because everyone knows it's not justified, but it still leads to a good deal of sweep-up, of people finding themselves talking about certain players in certain ways perhaps in spite of themselves, because the hype machine's whole aim is to make them do so. So, in a way, the whole way he's talked about is a bit unjustified.