Good question - main thing is that it's saving time on repeatable searches and optimize search.

I was working with Elixir without ability to use LSP and so, my flow often looked like this:

    > rg "defp|def\b|def_rule|def_helper" . | rg "something"

Only to find that someone made a "def_instruction" and it's there. I didn't want to filter our, I just wanted to... sort.

With config file I can do a simple

    > rg "something" | ssort ~/ssort/elixir_methods
    > # or if I use it often
    > alias ssort-elixirm "ssort ~/ssort/elixir_methods"
    > rg "something | ssort-elixirm

This can be solved by working LSP though, what working LSP can't solve though is:

    > rg "impl" | ssort-elixirm | ssort -f MyCompany

But (given as it looks like it was buried) it's a microoptimization for CLI search freaks ;)