User blog comment:FairyRaven/Fairy Tail Chapter 371: Tartarus Arc, Part 2: Song Of The Heavenly Dragon, Review and Commentary/@comment-5303512-20140214094734/@comment-7418318-20140214123511

You could say that on Tenrojima Natsu lost to Gildarts, but was the scene bad because of it? No, quite the contraty. It has been the biggest character growth Natsu ever got in the entire series.

Zero knocking Natsu, Lucy and Gray unconscious in Nirvana was also losing. In the Phantom Lord arc they lost when they attacked and were forced to retreat. On Galuna Natsu and Gray both lost to Lyon once.

Losing a battle sometimes is the best way to show just how dangerous the enemy really is and thus gives the later victory in the re-match much more meaning than winning against someone who never managed to acomplish anything.