I'm not sure how you missed it, it's right there in the summary: "Infinigen is entirely procedural: every asset, from shape to texture, is generated from scratch via randomized mathematical rules, using no external source..."
The sheer scale of what this does, how general it seems to be (instead of a single special-purpose animation like in the demoscene), as well as the fact that the output is structured and labeled assets I would consider novel, and very impressive.
"Ours is entirely procedural" == ""Infinigen is entirely procedural"
"relying on no external assets" == "every asset, from shape to texture, is generated from scratch via randomized mathematical rules, using no external source"
If that doesn't make it make it clear, could you elaborate on the part that doesn't click and I'll try and explain further.