I don't think we can prove anything either way, especially just us here on the forum. If someone says they have DPDR but they don't have anxiety, someone can always answer that maybe they do have anxiety but don't realize it (which can't be proven either). And if someone says that everybody who has DPDR also had anxiety, you could always argue that maybe they have just ignored all the counter examples, or explained them away because it didn't fit their hypothesis. Even in that paper, if that woman got cured from DPDR while having anxiety, it still doesn't prove it wasn't caused by anxiety, maybe for some unknown reason coming back to stronger anxiety could cure something caused by anxiety. I don't know why but I wouldn't be that surprised if it was the case. Who knows? My experience also doesn't make this clear for me, I am certainly not a serene person, but at the same time I have had extreme anxiety years ago and my DPDR did not get any worse at all compared to my best day. But who knows, perhaps DPDR increases with anxiety and then saturates at some level and stops increasing whatever the anxiety level? Or maybe it doesn't, perhaps it is not caused by anxiety at all but by something unrelated that occurs more frequently for people who have a natural tendency for anxiety and there would be a correlation without causation. Who knows?
Personally what bothers me is to pretend we know for sure either way. Literally anything is possible and there are many different cases with different symptoms. Clearly, some people have terrible anxiety, to the point they can't even work or leave their home and once they face it it all goes away. And at the same time some people never had this kind of problem, have a job, are not disabled by any anxiety, every day they are doing the very things that made the other person recover and more and they still have chronic DPDR. We clearly don't all react in the same way and it is clearly not the same thing for every one.
In my opinion there is no reason to forbid the exploration of one recovery way or the other. Which is what we do when we say that our way must absolutely be the right way and the others don't make sense. If each person does their own stuff depending on their opinion and come and report back on what helped them specifically, maybe we can learn more things and it can help someone. But I don't think we are going to figure anything out about dpdr that will work for everybody.