It took the JS community many iterations to get to vite. Building it into the language just means you get stuck with a "good enough" solution that survives by inertia. We'd still be using webpack.
I'm all for building things into the language when there's only one way to do it though.
for sure! but there are lots of incremental shareable primitives that could help. I think about go's built in testing tools that can get extended as an example