Oh geez, if you want to play the linear game, you can even trace the Android development to the Roman empire.
To put the conversation back in a grounded and reasonable list of arguments, let's start with the premise that technology != business.
So even if the tech that Magic Leap is creating is so great, by the time they go to market, they will be competing with an ecosystem already in place. Apple will have all the apps that have been built with their ARKit (not to mention their App Store monetization strategy). Sony, FB/Oculus, HTC and MS are already at the infancy of developing something serious there. If Magic Leap came out with a product today, they are already starting behind.
If we take in consideration price point, it even becomes a more challenging scenario.