I see a ton of posts linking to "reviews" by Olympus or Panasonic" "Visionaries".
These are not reviews. These are sales demonstrations with all that entails.
It may surprise you, but a "reviewer" cannot learn how to get the most out of a camera or lens without thoroughly testing it. This is especially true for high end cameras and lenses that have very sophisticated software programming for use in birding which is technically way above taking pictures of Mom and Dad or your favorite church. A day or two by someone unfamiliar with the intricacies of a system is like you or me doing a "review"; pointless.
I know from my own experience that it took me 3 years to get to the point where I could get the most out of the EM-1 I; and I have now the EM-1 II for about six months. Three weeks ago I bought the 300 F4. I was out on the 2nd, 3rd, 9th, 10th, 15th, 16th and 17th and my level of skill with that combo is still quite low. Yes, I can shoot landscape with that combo (although it is rare I would use that focal length for landscape) and I can get great results on focus stacked mosses/lichens, and largely stationary birds; but I can barely shoot birds in flight; which is highly dependent on very sophisticated software programming and menu mastery of high end cameras.
So, when I want to truly evaluate a camera or lens, I look to those with the most experience with it (them); not the least. Those are the folks who can truly evaluate how precisely a new camera or lens performs.
These guys are demonstrating a camera, talking up the good points and ignoring the downsides in the hope that you will buy the product they are demonstrating.
This is, of course, demonstrably false. If you don't watch by your own preference the reviews by Olympus, etc. visionaries, you would not notice that they mention in some detail what they would like to see better.
As to your "reviewers" - I assume you mean like Northup - they may have likely have had the opportunity to have "tested" the specs of many cameras, but are only likely to be skilled at evaluating the performance of the camera models (and lenses) of the system they personally use. In reviewing their "reviews" I always look to see if they - the Northups of the world - take images comparable to what I hope to be able to take from new gear I might be interested in. I'd bet as to photographic skill with 40 years of experience I am as good a photographer as most of them. There are exceptions of course, like Petr or Tipling as examples in the field I am most interested in - but they are professional photographers not professional "reviewers". They are experienced with gear and most often don't voice an strong opinion until they have thoroughly vetted a camera for weeks or months in their areas of expertise.
You can learn some basic things by reading reviews as to some of the functions a camera has - like ND filter - but this tends to be at a very basic level. Some are more sophisticated in testing as at Camera Labs where his tests five years ago showed relative noise levels for the EM-5 sensor compared to the EM-1 sensor at long exposures over 15 seconds at ISO's of 1600 and 3200 - which is relevant for astro/landscape. But that is an exception.
