I really, REALLY agree with this philosophy. I think something to keep in mind, too, is even if you feel like your story "has been done before" by someone else, it hasn't been done BY YOU YET!
Every individual has unique details they can add to existing genres of any kind. Even if you don't feel like you have something ultra original (or even if you want to post fan works), people ALSO love tropes and familiar subjects! Some things are cliché for a reason, and the reason is they're fun and enjoyable, even if we see them often
so I wouldn't stress too much about an idea not being good enough or original enough.