(True, but I think most of use were also sleeping while she was talking to Kaitlyn. While she is a leader of a brigade so far in this adventure she hasn't done anything leadership like for the group unlike Reva who has plans of action and Prospero who seems to be wise and know the area, despite his slight insanity issues.
Talyn would also count for her wisdom but her massive pride holds her back from being an effective leader, as seen with the with the boar situation.
Another thing is that Prospero and Reva have never once had a situation of prejudice or distain against another member, Luna still doesn't see beyond Prospero's lecherous moments, and while Sarah doesn't hold ill will against anyone she can be very harsh and point out a flaw without restraint, even if she didn't outright say it to Talyn she really didn't hide it nor did she want to because again she was concerned about Talyn's seemingly lack of discipline.
There's a lot of factors to being a good leader and just because Luna's led a brigade doesn't mean she's a good leader for the group because the knights probably don't have our quirks.)
(There's more to her than simply leading a brigade. Much more. As I'm sure there's more to everyone in the group. And she doesn't hate Prospero, she's just disapproving of his lewd behavior (remember, she believes the body is sacred), and him swimming while everyone was working hard didn't help his image, in her eyes.
But, that's just how she was raised; she firmly believes in strong work ethic, the sanctity of each individual and respects everyone for the most part, even Prospero, in the sense that he's not scared to hold back and can stand up for himself no matter what. She respects his strengths and she has to accept what she sees as his flaws. Because she's such a strong believer of principals, it's a bit difficult for her to accept the ones she's uncomfortable with.
And of course there's more to being a leader than leading a group. You need extreme patience, generosity, the ability to work well with others and acceptance of different point-of-views; the latter of which Luna is working on.
There's a reason why I stated that she completed the 3 Trials of Avalon; it's no small feat and tests how trustworthy you are, your stamina and strength of heart. She's not just a simple mage, and I don't see how the brigade of Knights wouldn't have quirks like the rest of us; they're no different. They're people, after all, so of course they all have very different personalities/views and it tested Luna's resolve and how far she's willing to go to protect her Kingdom.
And really, everyone in the group has the potential to be a leader, but we still don't know each other well enough, which is why Luna declined to being one; she has to prove herself to them, even if she knows she has experience with being a leader. Reva is the one with the map and knows the lay of the land, making her the most viable candidate, at the moment.
Anyway, sorry that this post is so long, I have a habit of getting invested in these things; as seen by my wall o' text response to Ruri about The Last of Us.)