The first thing you need to know about BiS in the current state of the game is that it's all based on min/maxing secondary stats. Now, you may think to yourself "Well, that's worth it, right? With enough secondary stats you could reach a threshold that allows you to do things you otherwise couldn't!" - which is a completely valid thought process to have. However, what you need to realize before I go any further is that no equipment in the game has enough points in secondary stats that it actually ends up making any sort of definable difference. As an example since we're talking about PLD - min/max Parry PLD set vs max accuracy, lowest Parry PLD set. The min/max set parries roughly 1-3% more.
From there, you might think "Well, that's very very little, but I might as well have it, right?" - and it's true, if you happen to get all the pieces then you SHOULD use the min/max set. But something important to note is that you can beat T5, easily, in the bare minimum set and MOST of your current BiS set is RNG drops from Coil 1-5 so that means you'll not only be relying on luck, but also sinking a large amount of time into those turns. Even when they're repeatable and you can farm them infinitely, you'll still be spending a massive amount of time trying to get current BiS when you could already be in T6 getting BETTER gear and progressing even further.
So you need to ask yourself - is it REALLY worth stressing over a BiS set that won't ACTUALLY make T6-9 any easier, all of which will be replaced almost immediately?
