Scale is not a prerequisite, but you do have to sell it to your company. If not a greenfield, porting a codebase over is not easy, and you have to do your organizational excellence homework too. Monorepo, well reviewed code, team not in permanent crunch, high-quality tooling culture.

Just like Kubernetes, Bazel is not a silver bullet. But if you get all your ducks in a row, switching over is a gamechanger and will help you out even at the smallest scale.