Audio reviews are far more subjective than video (which is easy to test and assess against actual industry standards), where audio is much more subjective in that respect.
If they are truly subjective then what is the point, as each person would consider how good the product is differently, making reviewing audio product akin to reviewing impressionist paintings ...
I suspect what people are asking is: for signal in, signal out, how high is its fidelity?
While the room has a much greater effect on audio than it does video, and you have to add speakers to the equation, this is a processor taking primarily a digital signal and poping out an analogue one.
If the fidelity of the product is poor than even with the 'best room in the world' and perfectly flat speaker output, it would still not be performing as good as another product with higher fidelity (GIGO).
Like testing a display in a batcave to determine its optimal performance, once you get the product in your own environment it may perform differently but objectively you've bought the best for your budget.
While it is no doubt true that some people will like a particular lack a fidelity (i.e. a pronounced bass or rolled off tops), that is the subjective part, and people should be made aware of that to decide if that is to their preference.
People paying for a high end product should rightly have extremely high expectations, someone paying a hundred or so quid for a soundbar should expect compromises, and it's fair that reviews are in tune with that. For the latter "it sounds pretty good to me" type reviews are much more forgivable.
As we've paid exactly £0 for these reviews we can't be too hard though.