I don't see explained anywhere what causes them to make the leap that, because the math of holographic theory works, the universe 'is' a hologram. Doesn't it just mean that they've found a way to convert between two abstractions?
Well the important thing is that they found a way to abstract it with less dimensions than they previously did. This means that the previous theory had unnecessary redundancy, so the new theory has less cruft.
The hologram is their way of describing how they changed their way of thinking to land on this new theory. So they looked at the problem with the idea that the interactions in our universe could be a projection of the interactions in some other universe.
The breakthrough is that they found such a universe ours could be a projection of, and that universe can be described with less parameters than the previous leading theory.
The smaller a theory is, the more clear its foundational relationships will be, so the closer we are to actually understanding why things are like they are.
So previously we had a big question, why does our theory of everything require 18 (or more?) dimensions to describe the universe?
And now we have a slightly smaller question: Why does our theory of everything require 10 dimensions to describe the universe?
