If we are looking at FFlogs, we are doing it for endgame content. Not for story dungeons. So while clearing the content is the only goal in casual content and not everyone performing decently is perfectly acceptable to a degree because there is no hard requirement to clear, in endgame content just aiming to clear it somehow and not paying attention to your own performance is just dumping more responsibility on others to the point of silently asking for a carry.
The goal of every clear party in PF is obviously to clear but someone slacking is putting the team at a disadvantage from the start and one they may not recover from.
Honest mistakes happen all the time but a team with some people performing way below average will not be able to salvage them as easily, if at all. Doing the minimum required for a clear if most others perform well is not enough in endgame content.
First clears are often messy semi-carries and they performed poorly. That's okay, everyone started somewhere.
But from then on it's everyone's own responsibility to improve independently from others. Even classes like Nin, Dnc or Ast which depend quite a lot on others performing decently have enough they need to work out alone. If the others perform well, too, great! But the first step is always to look at themselves.
I think you're underestimating the amount of things FFlogs and xiva can tell you.
You can see exactly who died at which time and to which mechanic, you can look through the cast tabs of other players and look up when and how often they used mitigation, you can see who took how much damage from mechanics, you can even watch a full replay and see how people positioned themselves and get an idea about their gear by how much their HP dropped during certain mechanics.
You have a full timeline for every single button someone pushed in FFlogs and xiva.
Reconstructing a fight based on all these informations is rather easy.
And improving in endgame content is first and foremost everyone's own responsibility. You do not need everyone in your party trying to equally perform better to improve yourself - this is your responsibility. Trying to put at least part of the blames on others is only going to hinder you.
I had some really chaotic parties with people dying countless times, positioning themselves poorly, not using mitigation, tanks with poor gear and bad cd management but all of that doesn't keep you from things like using powerful oGCDs, paying attention to your uptime, regulary refresing your dot etc., if you try.
Your performance starts with yourself, not others. The better you are, the easier it will be to handle every type of party, from the smooth steamrollers to the chaotic bunch of headless chicken.