There's a million ways to fix it so this important experience isn't ruined for new players, and yet Square Enix is still refusing to do anything about it. This is the biggest single flaw with the game IMO.

Here's just SOME of the ways this could be easily fixed or at least improved:

-Barriers preventing anyone from advancing while a new player is watching cutscenes, with a tomestone bonus to make up for it
-ilvl sync, making waiting for everyone more appealing, again with more tomes as compensation
-Reduce the dungeons to 4 players (This should be done no matter what honestly)
-Make a special exception in the Mentor roulette where the new player is paired with one or two unsynced level 60 mentors for an easy(but not over in a blink), hopefully friendly run
-Make the dungeons possible to complete solo, with NPC party members

But no, they just keep them in the same terrible state they are in, and sour the game experience for every new player who is playing alone.