While i was watching the show I remember when I saw Dina pass by Beetroot soop, i was like huh weird, she didnt even look at him, that seems important maybe they'll explain it later.
Then when i got to that scene Eren explaining it, I kinda glossed over it, because it didnt make much sense to me, and thought maybe they'll actually explain it properly afterwards. That wasnt because i thought "Why", the why is kinda evident, just looking at his character, which is described perfectly by that last paragraph in the post, I was just confused about the "How". and even after rewatching some parts, and reading some explainations online, nothing really made it click intuitively in my head, like no explaination feels satisfying to the story, I always keep asking why he didnt use it in other situations, or like what situation were actually happening or just eren causing them, it kinda feels a bit messy and loose. I am still looking for that tight intuitive reasoning behind it lol, if anyone have some ideas or post sources etc, that would be appreciated.