That's a good point, and one that I've forgotten since I've been out of the JS world for a while now! Often you're trying to run the code in different environments depending on the context, which does require a lot of extra build tool support. Consolidating that is a reasonable goal, I'd say.

It will be neat to see where they draw the line. For example, will Rome include an assertion library? What about mock and fake support? That feels a bit far from what Rome is trying to do, but if they've implemented a test runner, maybe defaults provided would be good for the DX?