There is one reason why FF14 would never have full ability on synch: it has way too many oGCD.

If the tool kit are mostly GCD then yeah no problem, having the full set just means having more option, and you can crunch the number. But oGCD = free attack, and there is no way you can crunch the number on a max level to make it content appropriate in a low level duty. Like on some classes you're looking at anywhere from 3-6 additional "free" attack, especially in the openers. The max level just gonna nuke the place down unless all of their oGCD is neft to a point where they're no longer worth it to even press the button.

And healers with their full oGCD kit in lower content? I don't think I even need to elaborate