Is there any evidence to substantiate this claim? As far as I'm aware above the transition frequency the direct sound always becomes dominant regardless of DI. All the evidence, when it comes down to preference, points towards wide horizontal directivity being prefered in normal sized listening spaces by a majority of listeners.
OK but I was speaking in general for listening, not specifically to any kind of conception of proper monitoring.
I'm not an audio engineer but my understanding as well is that this conception of "the direct sound must be dominant" is due to historical monitors with terrible directivity and not research-based or anything like that. So I'm not really sure it applies to speakers with perfect directivity like Genelecs, especially if they're in a non-studio environment that doesn't have a lot of nearby angled, flat surfaces like the console to cause strange reflections.
E: Genelec's guidance just says that past a certain distance, the room may colour the sound more, but they don't really suggest whether that's bad or good, so it would depend on the room of course.
While it seems true that there is a historical portion to this thought process, it also seems to be the genuine preference of some listeners, even if a bit of a minority. Directivity width doesn't seem to be quite like FR or or off-axis smoothness where almost everyone prefers the flatter/smoother result and it makes sense to optimize for something close to flat. Most people seem to prefer more sidewall reflections, but some do prefer less, especially mixing engineers. So I think it might make sense to want to have narrower directivity in your far field monitors than your near field ones as
@ferrellms says, especially if you want to match the tonality with the nearfield ones.
This seems evident in Harman's own speakers. On the whole, JBL monitors have narrower directivity than the Revels meant for at-home use. Not crazy narrow, but narrower nonetheless.
It makes sense in my view that for monitoring purposes one listen to what's coming out of the speakers with as little room-interference as possible.
I would add that I prefer narrow directivity or little side-wall reflection because I can hear more of the recorded ambience cues.
As I always think of it: narrower directivity transports you to the recording venue, wide directivity transports the musicians to your room. That's very much a matter of preference, and I can see why some like you prefer to have fewer sidewall reflections. You will absolutely hear more of the recorded ambience cues with narrower directivity speakers. For me, the effect is never fully convincing sans surround speakers and it ends up sounding a little dry which is why I prefer wide. But I do miss out on the sharper imaging sometimes.