I know what Flash is supposed to do traditionally, but it's not fine as it is. Flash fills the same spot in the tank tool kit as Overpower and Unleash do, both of those inflict damage and make it so PLD AoE DPS is significantly behind the other tanks. That is an imbalance. Flash needs a damage component, or it needs to be replaced with another ability that has one. Enmity is not the problem, damage is (and nobody cares about the blind).
ATB systems were used through FF4-9, then again in 10-2, 13 and 13-2. FF10 used a turn-based system with no ATB (think they called it 'CTB' Count Time Battle). None of these ATB system are strictly turn-based, in the sense that they do have a real time component when toggled to "active" instead of "wait."
The major difference between the 4-9 era and all the things that came after that, is that in the early days of ATB, enemy and player turns couldn't happen at the same time. However, after X-2, 13 and so on, this changed and it was in fact possible for different turns to happen simultaneously. All the actors in battle had their own ATB gauges. These systems are very similar to FF14 but they've added a movement component as well. If all those elements make FF14 a 'real time battle' to you, then that's fine, it's really a semantic question. I think it's more of a hybrid system, like all the other ATB systems, where they combine real-time elements with turn-based elements.
Now, when I said ATB is GCD, I meant more specifically the ATB gauge mechanic. Whether you wait until '100' or wait '2.50' is completely irrelevant, mechanically it's a timer that you wait for to use your turn. Maybe GCD has connotations that I'm not aware of, but in the context of FF14 you could use both interchangeably. I actually find it weird they used the term GCD from the start, instead of ATB, considering the history they have with ATB systems.