If you look at configuring a tool like Jest, there's a ton of "build tool" overlap, typically involving configuring Babel/TypeScript, parsing, path aliases, and so on. In particular, you usually have duplicate configuration for Jest and Webpack for all those things, but with completely different config file formats. Test runners also need to be able to iterate over files, run checks, and print diagnostics.

Those all sound like things that Rome has the ability to do already, _and_ it's another tool that Rome could eliminate from a typical install.

I'm not planning to switch to Rome any time soon, but I definitely understand the mindset involved in that approach.