[quinnirill]

This is to avoid multiple versions of Trine required by libraries (or the application itself requiring a different version of babel-runtime) causing the different versions of `babel-runtime` to be included multiple times, which would be a problem especially for browser applications. Trine itself is very small, but if each module introduces a dependency to babel-runtime, it would be another case of "npm downloads the whole internet". :/

[loganfsmyth]

To me at least, that's more up to NPM to manage though. As it is, it means you're essentially sidestepping npm. There's also no guarantee that people will install a version of babel-runtime that is compatible with the version of Babel that you used to publish the code.

It also means trine can never upgrade the version of Babel it is using internally, since Babel could change the helper name that it uses or something, but that might not exist in the version of babel-runtime being used in the code that depends on trine.