It would be completely arbitrary and clearly motivated only by saving the appearances, but yes, you pretty much need a hard fundamental limit to explain why they are so epiphenomenal despite such cosmic resources. There’s no plausible story where they can manipulate the mortal realm enough to screw with pilots but also we observe the universe exactly as it is. (And the easiest hard limit is simply that, like regular aliens, “they don’t exist”. It is hard to change the universe noticeably when you don’t exist.)
Unless you posit some fundamental limit on possible intelligence/computational power for field-beings. Would that be too implausible?
It would be completely arbitrary and clearly motivated only by saving the appearances, but yes, you pretty much need a hard fundamental limit to explain why they are so epiphenomenal despite such cosmic resources. There’s no plausible story where they can manipulate the mortal realm enough to screw with pilots but also we observe the universe exactly as it is. (And the easiest hard limit is simply that, like regular aliens, “they don’t exist”. It is hard to change the universe noticeably when you don’t exist.)