Saw Jenova and I had no choice but to reply, because we Sons and Daughters of Jenova must stand up for one another. We may only have 5000+ members according to XIVSoul, but at least we don't belong to a server with a silly-sounding name. I wouldn't even name my dog Balmung. **
I'm a relatively new player who recently joined an FC. I joined a big one. The reason I joined a big FC was because I had every intention of becoming a serious player in the game, even though I joined the party late, and I wanted to surround myself with great players whom I could learn from. I don't care much for the drama or the excessive trash-talking. I even tolerate the ilvl 120 kids who make it a point to let everyone know how much of a badass they are IRL. It's almost as if some of these people aren't even here to play the game, and they pay a monthly fee solely for being able to have a group of people to talk to. I turn a blind eye towards all this and put my FC chat on Log Window #4, because I figure that this is a small price I have to pay for the chance of one day gaining access to the very best players in the game when I'm ready.
Being a new player with nothing to offer, I ask not what my FC can do for me, but I keep my head down every day, do all my solo quests, line up in DF for group quests (how dare I ask them to join my lowly Lv. 2x Halatali party), craft all my own stuff, pay my dues at the company chest, and when everyone logs off, I log extra hours to silently help out all the green sprout newbies who have trouble finding all the quests they want to unlock the content they want. I do all this with the hope that one day I might achieve a sufficient level of proficiency that it would not be considered a heinous insult for me to ask the officers and supreme leaders to teach me about EX Primals and coils and so on. (I'm not even thinking about Gold Saucer, because fun is the exclusive privilege of the accomplished heroes of Eorzea who have rightfully earned their vacation by saving the world, at T13 and beyond, more times than I've successfully mined copper ore.)
This hope is why I stick with my FC. My eyes are on the prize. Not quite the answer you are looking for, I know. But I have a feeling that I am not alone, and somehow I feel like I need to remind people that level-headed, hardworking, drama-avoiding players like me exist, and all we want to do is to play the game, and play it well. More to your point, I believe that these types of players can potentially be hugely beneficial to achievement-based FCs, if they can create the right environment for it.
(** Sorry for the quick jab at Balmung. But I'm a guy who refuses to play as a pugilist because the punching sound effects are awfully unsatisfactory, unlike slashing. What can I say, satisfying sounds are important to me.)