There shouldn't be a Myth cap because.....

[Eekiki]

How was it reconstructed from scratch? They had a story, a world, primals, jobs and classes. Yes they did change and reconstruct the world, the battle system, created an additional storyline, and added more content, but it was all based of a pre-existing game. They made an endgame and prettied it up, so how is it from scratch?

All of those things, plus they programmed a new game engine. They built new data centers with new server infrastructure. Don't just look at what's on the surface. It's much much more than what you see.

It's more accurate to call this game a sequel of FFXIV than version 2 of the same game.