I have to say, I struggle to visualise what I would expect from something lit with ACEScg primaries. Since it’s not something any of us have experienced in reality, it’s tricky. There is no doubt the image on the right looks more pleasing. But is it truly representative of an image lit by monochromatic lights which are on (or in fact slightly outside) the spectral locus?
I would say it feels to me like the right hand image is lit with fairly bright, saturated red and green lights, and I can try to imagine what the lights I think are lighting it look like. Maybe like traffic lights, but definitely real world, plausible lights. So if a DRT has to map non-physically-realisable ACEScg lights so they look like the effect of real lights, what would it do with those real lights? It would by definition have to map them to something less saturated. So everything gets desaturated to make room at the boundaries. I think this is the reason a lot of stuff looks rather “muted” under @jedsmith’s DRT.
I really am just thinking aloud here. I’m not saying the mutedness is necessarily a bad thing, if it can be overridden with an LMT. It could be compared to the complaints that go round in circles here where people say ACES is too dark because it doesn’t map diffuse white to display white like the sRGB VLUT that they are used to (it’s a similar “making space near the boundary”). But I am slightly wary of judging a DRT as being good because it makes pleasing looking renderings of CGI with super-saturated lighting where we have no real world reference for what it “should” look like.