That works somewhat for finding uses of a native Go module, although I've seen lots of cases where the module name is autogenerated and so you need to import with an alias (protobufs, I'm looking at you). It also doesn't work quite so well in reverse -- you need to find files with `package url;`, then find instances of '\bfunc Parse\('.
Lastly, one of the bigger issues is (as aforementioned sibling commenter mentioned) the application of this principle to methods. This is especially bad with method names for established interfaces, like Write or String. Even with a LSP server, you then need to trace up the call stack to figure out what concrete types the function is being called with, then look at the definitions of those types. I can't imagine wanting to do that with only (rip)grep at my disposal.
Lastly, one of the bigger issues is (as aforementioned sibling commenter mentioned) the application of this principle to methods. This is especially bad with method names for established interfaces, like Write or String. Even with a LSP server, you then need to trace up the call stack to figure out what concrete types the function is being called with, then look at the definitions of those types. I can't imagine wanting to do that with only (rip)grep at my disposal.