That advice is a bit old now, although it might become viable again once core is pulled into the compiler rather than a dependency.
Personally, I completely disagree with committing generated code - of any form - to source control. And that also applies for publishing to NPM.
Libraries can’t be expected to publish every flavour of modules ReScript can generate, and in fact if your dependency was last compiled with an old version you may find incompatibilities with the generated code (for example the swap from curried to uncurried by default in v11).
It’s much safer, and usually not very difficult, to run rescript during the CI process.