What you're referring to is "mystique", which is no description at all. It is neither qualitative, semi-quantitative or quantitative. Such "reviews" are not based on any established evaluation criteria and therefore negate objectivity (although they can be excused if they provide decent SOOC comparison photos). How can anyone rationally part with $2000 or even $200 or be dissuaded from doing so on that basis?
Practically speaking, no one, including yourself or Dpreview, is going to buy all the aforementioned 70-200s, take thousands of photos with each and then describe their merits for one genre of photography (i.e., portraiture). In the absence of a universally accepted test methodology, brick wall/ test targets/ MTF curves and even pictures of a household cat may have to do.
OK - "even pictures of a household cat may have to do" ?
I'll send you all some I took a few weeks ago with my R5, RF 70-200 f2.8L, with a B+W XS-Pro Clear Nano filter. Handheld, animal eye AF, electronic 1st shutter & mechanical 2nd shutter, raw on all. DXO Photolab4 (& deep prime) to my taste in post. Originals are slightly cropped for best look, then resized to 2.5k pixels longest side to download here, and are followed by a 1:1 crop around the face & eyes to show sharpness.
*EDIT* - I've been reading a lot more about the benefit/downsides of using any clear protective filter in general, including the highest quality ones. I'm now going to take off the filters for most usage, and only put them on when in dusty/sandy environments.
iso 400, f8, 1/750", 70mm
iso 400, f8, f/1000", 70mm
iso 400, f8, 1/500", 70mm
iso 100, f2.8, 1/1000", 135mm
iso 400, f8, 1/1000", 200mm
OK - I might not have photos from other 70-200 bodies & lenses to compare to, but I just thought I'd have some fun sending these off to all of you to enjoy.