I suppose, but then what stopped them from merging once again? Did they require the Frozen Flame, since they sent Harle to steal it? Or was that just a trophy they took on top of destroying FATE?
Perhaps the former: perhaps the Frozen Flame was required to "break the spell", so to speak, of splitting them that FATE had cast.
The alternatives to this scenario that I can see, the ones that keep the splitting up of the Dragons and the sealing of their powers as one event, are:
A) It was back when the Dragon God was one that it was worshiped as a god, and when it was split up and sealed was when it began to be forgotten.
or B) It was the split *and* sealed Dragons that were worshiped as gods.
Both of these have problems.
A) is contradicted by Belthasar's aforementioned quote that the Sea of Eden was where the Dragon Gods, plural, resided. It is also contradicted by every other mention of the history of the Dragon Gods by people in El Nido, who never mention a former state where the Dragon God was one. A case in point by Direa:
The gods that represent
each Element are called the
'"Dragon Gods."'
Since they symbolize the
powers of nature, they are
also commonly referred to
as the '"Gods of Nature."'
If the glory days of the Dragon God's power, and hence its worship, were when it was one being, then those most devoted to their religion should retain some cultural memory of that state when it was one. And indeed, if the instant they were split, their power waned, then that state should be downplayed by the devotees, rather than glorified.
B) is, as stated before, at odds with Belthasar's statement that when FATE sealed away their powers, that was the beginning of the end of their recognition as gods and their influence over most of the people of El Nido. There's this aforementioned quote by Belthasar:
But then FATE sealed away
the Dragon Gods' powers, in
effect becoming a god itself.
Thus the islands where the
new godhead, FATE, existed
came to be called the
Sea of Eden instead.
And a little later:
At that moment, the seven
Dragons who had been
rendered almost powerless
and forgotten...
So these two quotes really seem to cement the idea that the Dragon Gods' relevance to the people of El Nido was contingent on them having their powers, at least most of them.
On balance, B) seems a bit more plausible than A) (and after all, the Dragons still pack a punch against the party, even when their powers are supposedly sealed), but if we take Belthasar's exposition seriously, then my alternative to both of these, namely that the splitting preceded the sealing of powers by several generations, seems most consistent with all the text of the game.