There are a lot of performance advantages along every step of the way, as you mention. I think you can look at this from many different lenses beyond performance.

A big advantage was how fast and easy this was to get up and running. Simplicity is key here - it's a simple API written in JavaScript (no config, VPS, etc necessary).

The other really important thing is scalability - when workers.dev went live, we didn't have to worry about being able to handle the spiky workload (preregistration sites end up failing quite frequently). This scales infinitely.