I don't think people quite realise how strong things actually are when compared to low level.

I done a calculation in this post here to highlight it. Granted, this is for PLD before the rework, but other jobs are going to have similar situations.

If I want to use a more recent example, again, PLD. I just tested this and I can kill a bat in Sastasha in 9 GCDs using only single target actions and no FoF. Adding up the potency for 2 combos (Fast Blade > Riot Blade) and then 1 Fast Blade, that is a total potency of 1790 to kill that bat.

Fast forward to level 100 potencies, that same bat would die in 7 GCDs using the same rotation. But PLD has access to more attacks, the combo isn't only 2 GCDs long any more. 1 full combo then Atonement + Supplication is enough to kill, which is 5 GCDs, but you still have a Divine Might Holy Spirit and Sepulchre, which, just with those 2, takes off about 60% of an enemies health. This is also before we take into account buffs like FoF or the insane damage locked behind Imperator.

As another example, BLM's Fire 1 in Sastasha is 252 potency after AF1, at level 100, with all the traits and AF3 is 556 potency, but wait, you don't use Fire 1, that has been replaced with Paradox, that would come out to 892 potency and that is without AF3 as I don't think that affects it, but you do spam Fire 4, 988 potency, yes, it takes longer to cast, but you are still doing close to 4 times the damage of the basic Fire 1 spell.

You can look at any job and see similar trends across the potencies and, it is all well and good saying, just reduce the potency, but where are you going to reduce the potency from? For melees, you could make the averages of your combos the same, but that makes the start of your combo weaker and the end stronger than the low level and doesn't take into account the massive burst potential. All a low level PLD can do in FoF is Fast Blade > Riot Blade, a level 100 is slapping Goring Blade and the Confiteor combo, plus extra oGCDs.

Which is another thing, oGCDs. With the vast array of ways they increase damage, not all of them directly potency related, it makes it even harder to just use some universal scaling. Monk doesn't get Riddle of Fire until 68, that is an extra 15% damage for 20 seconds every minute, which then later gives them access to Fire's Reply, for even more potency.

This is not something that is as simple as people make it out to be, you have to remember, we aren't just balancing level 100 against content lower than them, it is also lower levels having to have the balance applied to levels lower than them as well. It is a monumental task that just isn't worth it when the sync does the job just fine. This is also before we take into account defensives and healing.

Now, this isn't to say the low level kits cannot be reworked to make them more engaging, they should and this should be the route taken. Plus, adding in more traits like Melee Mastery, that just increase the potencies of things can help keep the low level scaled properly and avoid the potency creep that used to happen.