This pairs with his bio-box motto “Rely on others” (Ch. 455) and the seeded New-World defeat by Kaido (Ch. 456) — see Kaido Named As The New World Power Who Defeated Moria. The full lost-crew / past-catastrophe backstory is a promissory note whose payoff lies forward of this window — keep status: pending.
Why this matters
Oda routinely front-loads a villain’s defining wound in a single line of mid-fight monologue, long before the flashback that explains it. Moria’s “I will never do anything on my own again” is a chekhov-explicit backstory hook: it tells the reader a catastrophe happened without yet showing it, priming the eventual reveal of the crew/dream he lost.