Why was the fuse an accessible protective device for utility providers in the early 1900s?

It was simpler and generally cheaper to manufacture than early complex mechanical switches.

In the early 1900s, the rapid expansion of electrical networks meant utility providers had an urgent need for widespread, affordable protection. The fuse, owing to its simplicity, was significantly less complex and generally less expensive to manufacture compared to the sophisticated mechanical switches that were precursors to modern circuit breakers. This cost-effectiveness and ease of production allowed for the protective devices to be deployed rapidly across the burgeoning network of homes and businesses, providing necessary security even on relatively low-capacity and inconsistent early power grids.