It's kind of true. Routing algorithms like Contraction Hierarchies and Transit Node Routing don't precompute every possible A-B pair, but they do store so many

It's kind of true. Routing algorithms like Contraction Hierarchies and Transit Node Routing don't precompute every possible A-B pair, but they do store so many "shortcuts" (i.e. the best route between common As and Bs) that a route lookup will quickly converge on one of these precomputed routes for all but its first and last sections. It's similar to the way that we intuitively navigate by car - if you drive from (say) London to Glasgow, you don't bother weighing up the many options: rather, you take whatever local roads get you to the M1 fastest, then follow M1, M6, M74, and then whatever local roads get you to your exact destination.