Yes.
On the one hand, you are right. On the other hand, RC is offered, which can not be used directly. What's the point of having options to record sound from a phone, connect a microphone, or upload a calibration file – if none of it actually matter? Wiim app might as well just have the option to upload a final file to adjust PEQ after calibration done in REW.
I'm not saying it's Wiim responsibility or something, because it's clear that it's not. However, if Wiim can bypass all these filters on the phone during the measurement, it's definitely something worth to do. It will surely be useful.
