Alt-tab out of fullscreen leads to a DirectX error and game closing.

[Soukyuu]

FFXI was designed this way, and FFXIV is designed the same way.. therefore it is not a bug. It's just a feature that was excluded for whatever reason. Either that, or SE knows nothing about PC programming (no offense).

It is not... a feature. From what I heard, it's only an issue about not loading the textures back into video memory after returning to fullscreen, which just causes the program to crash.
Since you don't have to unload them when alt-tabbing from windowed mode, the game doesn't crash there.

That's what you would assume, right? But who really knows?

That would kinda imply SE is too stupid to think of anyone using windowed mode to bot instead of the crashing fullscreen mode... i really don't think they are that naive.