I think if you look at languages that support them natively, like F#, OCaml/Reason, or Elixir/Erlang, you'll find plenty of examples of real-world uses. Whether those would suffice to illustrate how to apply them in a JS codebase that has this proposal enabled, I cannot say.

However, having gotten used to having them, I can safely say I'll always feel hobbled to work in a language that doesn't have them, so I'm very much in favor of adding them to JS, whether or not this is the proposal that wins out over time.