Emacs and LLDB

Well, it is true that they went from providing what was viewed as a relatively full service development to something that is viewed as limited is certainly true. Some of this is perceptio. Some of it is low-quality overly verbose languages. But a lot of it is working with extensive classes and frameworks that the user can't possibly be expected to know, and advances in refactoring workflows that are well-supported at least with a subset of languages.

The short version is: codebases got bigger, and more powerful tooling to interact with them became more important.

You can get decent support for this kind of work in vim and emacs, but you have to be quite savvy to set it up, and it's a rare developer who does.

I certainly have never really looked to the FSF as a complete development tools provider though. Even in the heyday of gdb and gcc, I still relied on things like cscope and proprietary instrumentation tools.