I don't think that's correct, the ILM team presented this technology in a video:
https://youtu.be/gUnxzVOs3rk?t=104
(paraphrased) "it was designed to both light the actors and be a background that we can photograph, so that we end up with real-time live pixels in-camera"
Also from the article you linked:
> If the content was created in advance of the shoot, then photographing actors, props and set pieces in front of this wall could create final in-camera visual effects — or “near” finals, with only technical fixes required, and with complete creative confidence in the composition and look of the shots.
I'm not an expert in film terminology but it does not sound by any stretch that this was primarily about lighting.
It was for was shot composition as well; the cinematographer could see how it would end up while shooting. The screens updated to match the camera position in real time (e.g. to show the rest of a spaceship whose door was a physical prop).
"The final animated VFX would be added in later; the screens were merely to provide interactive lighting to match the animations." -- https://ascmag.com/articles/the-mandalorian, discussed here: https://news.ycombinator.com/item?id=22378679