Yeah the way things are is very naturally when one only compiles end-to-end --- there is little economic incentive to keep the internals modular when the productivity costs of entanglement only show up with a delay (and also programmers are not really compensated for productivity...).

It's really good in this new LSP era good tooling is increasingly "mandatory", and language implementers have to deliver. (See also https://ollef.github.io/blog/posts/query-based-compilers.htm... .) The higher standards of users (and aspirations of DARPA :)) are now providing the missing economic incentive.