> Let’s take it for granted that materialized files on the file system are the only way to go, just like first party code is stored on a file system and in version control.

This seems like a fairly large thing to take for granted, and I'd love to see what they think works. With the java project I work on, I'm fine having gradle inject the gradle cache paths for the libraries into my IDE.

I get the missing functionality, but would it really be wanted in the dependency managers directly? It feels like plugins or standalone tools are actually a better place for the more opinionated things or tools which require non-trivial source analysis to work.