No matter how you look at it, published accuracy specifications are far more imaginary than a specific instrument's calibration data.
I see a TE industry where a lot of the accepted product specifications seem to originate from the marketing department. And that is probably fine, because at the end of the day you need to make a product that will sell. But on the flip side we have plenty of products that can be hacked to higher performing models and of course as I mentioned, products that exceed their published specs by a significant margin.
I specifically did not mention calibration certificates, only calibration data. The data is literal proof in print that a "meter actually reads to 10X its spec". Also, it has the temperature at which the calibration data was taken, so you can match that environment.
In all areas of life we have hobbyists who push things to the limits, both dangerous and not. Industry, especially for paying customers, takes a much more conservative approach and has to account for a TON of variability, with regard to how standards are enforced, human nature, manufacturing variability, the list goes on...
So with that in mind, there is nothing wrong with a hobbyist discovering that their test equipment performs far better than expected and then capitalizing on that fact. On the flip side, it is definitely wrong to blindly trust a published spec and/or calibration certificates and that is why many industries have proving requirements as well.