Despite the description on its website, at core, there's nothing particularly geospatial about pgRouting. You don't need PostGIS, or even Postgres's built-in geo types (point, line, etc.), in order to use pgRouting.

Rather, pgRouting is a set of general graph- and path-search algorithms, exposed as procedures, that operate upon rowsets (most efficiently, upon indexed tables) of vertices and edges. You can use pgRouting to do SPARQL-like graph queries, or even full-blown network analysis, if you like.

In a previous job, I did just that: I loaded up social-network data into vertex and edge tables, and then I used pgRouting's implementation of Floyd-Warshall and Driving Distance to discover high-value potential social connections within a given relationship-weighted distance of a given user. Not as a one-time data-science thing, but as the backend of our service's matching engine, that ran every time a user refreshed their "candidate matches" page. It was pretty instantaneous.