Adam had only recently learned about the Monster Nexuses. For the most part, this was a thing of the past, since virtually none of the new Phantoms possessed the Monster Nexuses.
Over the past ten years, thousands of Phantoms have appeared, but only two of them had the Monster Nexuses. Those were Sano and Natta. Obviously, they weren't ordinary Phantoms, since they worked for Aiden.
Thus, excluding Sano and Natta, there hasn't been a single Phantom with a Monster Nexus in the last ten years. It was an extremely rare occurrence that has all but disappeared in modern times.
The main reason for this was that regular Nexuses offered no less combat power but were far safer to create and use.
Also, no matter what type of Nexus a Phantom had, if he was advancing toward greater power, sooner or later everything came down to a single point - the Manifest Nexus.
