Pern is actually described as being metal poor compare to Earth and lighter gravity, although not light enough.

McCaffrey eventually got tired of people pointing this particular thing out to her and did what she probably should have in the first place: Dragons fly in part using telekinesis and the wings are for control, not propulsion. Which as they already have telepathy and teleportation is fine with me.

But yeah, I never got their relationship and they stayed together for decades!