only if your definition of 'everything' is limited, all the refactorings in a half-decent ide are quite hard to get right with awk & sed. For what is worth, even something as simple as finding all elements in a type hierarchy are quite unobvious to do with shell tools for me.
FWIW, for other types of refactorings (I mainly use Java):
1. Change the name/type of something
2. Compile
3. Work through the errors fixing stuff it broke
But thank god I don't work on large systems like that.
I agree that, all the things you can do with automatic refactoring you can do with a change/compile/fix loop, but it imposes an higher amount of friction, which (even in a subconscious way) pushes you into not making changes.
As a ruby and python dev using vim, I can even feel this in changing a single method name (with sed, obviously not syntax aware), as a java one without a supporting ide I'd seldom venture in a "extract superclass and use it where possible as return value" kind of change.
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.
The main thing is just to get good at using the shell. Grep, awk, etc etc With all the tools at the cmdline, you can do anything.