It takes seconds or more to grep for a function, especially if it has a common name. It takes milliseconds to Go To Definition / Find Usages (either with an IDE or a LSP extension for any text editor).
If they're not using fzf, ctags or LSP at all, sure. But find and grep absolutely have their place, and I tend to use them even when using IntelliJ/VSCode.
Yes, no one said find or grep are useless, far from it. The original premise was people using grep to look for a function in a code base, or find to get to a file (presumably to get to an include file or imported module by name). And they are definitely sub optimal for this - as you mention, even outside of an IDE, there are plenty of better tools to integrate with vim or nano or ed (the standard text editor!) or whatever you prefer.
And then you go full circle when the project is bigger and Find Usages no longer works across projects (specifically in the context of a typescript monorepo) and it's back to grepping for usages.
The premise is that using proper code navigation functions will increase productivity over grep. Not that using an IDE will increase productivity over vim, assuming you use actual code navigation tools in vim.
As for the click: all IDEs and all code navigation tools for popular text editors like vim or emacs have full keyboard support. And M-. Or F2 or whatever are much quicker to type than "grep function_name".
