> Raising graph analysis to the level of linear algebra is brilliant.

Adjacency matrices is how graph problems were handled by APL programmers in the 1980s, mostly because there was no alternative before nested arrays. At the time, there was not a lot of vectorized hardware, and main memory sizes were too small for many problems, so the adjacency matrix representation was more of a problem than a good solution. It's really the advances in vectorized hardware and main memory sizes that have made this technique practical for large graphs.