I guess I didn't bring the point over clear enough. There is a difference between "in your face" hints of the likes "don't let him get you" and showing you an example/hint of what you have to do. They could have did it differently, namely by just letting the stalker catch up to you and stab you - you have a hint (treasure hunters dying) and punishment for not following the hint (you getting stabbed)
With AoE the hint isn't that subtle, yes. In 1.0, we used to have to watch the monster for hints, their pose switched depending on what they were going to do. For example watching Ifrit's leg positioning to anticipate eruption - which gave a visual hint by itself.
With twisters, you do get a visual mark, the small vortex appearing under you just before it blows you up - the problem is that it looks similar to, say, eruption's visual hint which tells you to go away - if you do that with twisters though, you blow up - inconsistent input to the user from the game that video I linked touches on as well.If people actually figured out how to avoid it then it means there was a subtle hint in game that provided them with an idea. Its just a matter of how obvious it was. Its more likely things hiding in plain sight that people decided to ignore.
I'm not really complaining about RNG, only about the seeming obscurity of the mechanic that is inconsistent with what the player learned so far.
My problem with "difficulty by obscurity" is that an encounter designed like that becomes much easier, sometimes trivial, once you figure out all mechanics, rather than to rely on actual player skill. This is not to say this particular encounter is easy, or that people will be winning against Twintania with ease now, but we just went from "unbeatable" (=difficulty level infinity) to "beatable with enough effort". That's already a significant drop in my eyes.