That's because many of the people who build those tools have coupled them to an IDE, rather than making a standalone tool that could be made to work with any ed

That's because many of the people who build those tools have coupled them to an IDE, rather than making a standalone tool that could be made to work with any editor with a little effort. And while it would be changing files without the IDE knowing, version control systems run standalone and modify file currently being edited, too - it's not a problem when you expect it. A standalone tool can either do static analysis (like a tag index, but more so) or communicate with the language runtime, and just leave the UI to the editor/IDE. Either way, it doesn't need to be in sed & awk.