Comment by itcmcgrath

One example would be where you have conditional logic that requires a database call. Without workers, everything would go back to the backend system, perhaps across the ocean. With workers in front you could shortcircuit that for all calls that don't require the DB call. You could also handle routing logic at that layer, allowing it to pick closer DB instances, etc.

[Disclaimer: Product Manager on Cloud Firestore who thought this was an interesting use-case]