Part of the fun is Mariner is a rebellious anti-authority rebel in STARFLEET. The mildest authority in the universe. Which is the only reason she hasn't been cashiered and even their near-limitless patience and tolerance is pushed to the, well, limit. It's an actual character flaw too and not just something to make her look cool, which it doesn't because as Ransom pointed out to her early on, "No one finds this edgy or cool. Just tiresome." Even Mariner admitted it to herself while beating herself up.