Seems a bit self-contradictory. They admit that choice does cause the belief in having more control as long as the person believes their choices are different.

Seems a bit self-contradictory. They admit that choice does cause the belief in having more control as long as the person believes their choices are different. The only thing they're really disproving here is that "if people believe their choices are identical, they don't feel in more control", which I'm not sure anyone ever denied? There's an important distinction between "someone's choices are identical" and "someone believes their choices are identical". I think any good D&D dungeon master knows this very well. Your goal as a DM is to make your players feel they can do anything, that they have full agency to make any choice they want, and that every choice is different. But it's also your job to keep the story going, so while you may vary the details -- a different encounter here, a different city description there -- in the end the player's choices don't change the outcome of the story much. Finding that balance where they believe their choices matter more than they do is what makes a great DM, and that entirely depends upon people feeling more in control when they believe their options are not identical.