Maybe I didn’t make myself clear. “Let it crash” is not something that should be thought of at the component level, it should be thought of at the system level. The fact that the application crashes “gracefully” or not is not what is really important. You should design the system in a crash-friendly way, and not to write the application and think: “oh, I believe it is OK to let it crash here”.
Then I don't think you understand how the phrase is used in Elixir/Erlang. The phrase is about letting processes crash.