with all due respect, it sounds like you have the privilege of working in some relatively tidy codebases (and I'm jealous!)

with a legacy codebase, or a fork of a dependency that had to be patched which uses an incompatible buildsystem, or any C/C++/obj-c/etc that heavily uses the preprocessor or nonstandard build practices, or codebases that mix lots of different languages over awkward FFI boundaries and so on and so forth -- there are so many situations where sometimes an IDE just can't get you 100% of the way there and you have to revert to grepping to do any real work

that being said, I don't fully support the idea of handcuffing your code in the name of greppability, but I think dismissing it as a metric under the premise that IDEs make grepping "obsolete" is a little bit hasty