Not answering for Kakiko but to give a little idea.
Privacy for one, yes I know MMO and all that but some level of privacy is allowed even in MMOs. I mean lodestone has options to hide your info or set it to friends only so why can't I with logs? But yeah, I enjoy having a mild bit of privacy and the ability to show this info to people I trust rather than leave it for any random Joe or Jill schmoe to search up. To be honest, if FFlogs had logs set to private by default rather than its current "You have to log into our site, link your character and claim it in order to set to private." system, I'd be a lot less...skeeved out by the whole thing but that is overall a different discussion.
Secondly, while I personally don't have much to hide, I don't like the idea of someone just being able to search up my character and attempt a "GOTCHA! YOU SUCK!" post or something. (No, not saying that's all people do with logs or anything just...it’s an example I guess?). But yeah, the whole "Someone being able to look up your character and see every raid, trial, and bit of content you've done." concept really creeps me out and I don't like that, so I hide that stuff to keep some form of privacy. If I want to discuss my overall performance or my track record with people, I want it to be with people I trust and know aren't going to be asses or condescending about it. (I know, I repeat myself a lot but it helps get the points across.)
Thirdly, cause it calms my anxiety down. I am a frickin' mess of anxiety, my mind will take tiny things and run them through every possible scenario it can till it finds the most frightening, crippling outcome and then constantly tell me "This is gonna happen if you join that PF. HEHEHEHEHE!" so having my logs and stuff set to private to have a thing to tell my mind "No it won't cause this is all set to private so they can't just look me up and do that." helps calm me down. Also if I'm kicked cause I won't share this stuff, then those aren't the types of players I wanna hang out with.
Fourth, because I can. Just because logs or the like are recorded by other people and posted without my consent or knowledge, does not mean it is suddenly everyone's right to scrutinize, critique, point out, or overall judge my entire career as a player. They are still MY LOGS and if I wanna hide them, then that is my right. This doesn't automatically make me a bad player it just means I'm exercising my right as a person, to a bit of privacy.
People hiding their logs doesn't instantly equate to bad/lazy/poor/shitty player who wants to be carried. Some people may have legitimate reasons to hide their logs or hide their info. So yeah, if you are saying "If you hide your logs, you are probably a bad player." Then yes, you are painting with a SUPER WIDE BRUSH!
I know someone is gonna come out and basically do a "You're totally wrong, lol." counter argument post and tell me how I'm stupid or something for wanting a little privacy and overall, I don't care. I was merely offering a few examples from my point of view for why someone might hide their logs and such and if you don't agree with them, that is fine but I'm not really gonna budge from this. I enjoy privacy and control over my own data and information. If that makes me a 'bad player', then ok, I'm fine with being a 'bad player'.
Anyways, have a lovely day and thank you for reading.