I agree with your statement. There will be some bigger and more expensive speakers that don't do as well as the 305 at compression linearity. But I also bet that the vast majority of them will pass those tests as well as the 305, meaning the test isn't useful for choosing which speaker to use.
Most audiophiles buy speakers for filling a room with good sound when placed away from the walls and listening distances of 2.5-4m, and if they are listening to good advice, they will be buying decent sized speakers with decent output and power handling for the job. I bet, when you take those speakers, and graph the compression linearity as per the above samples, at 86 and 96 dB at 1 metre, they will all get a pass with non-meaningful differences.
What I would like to see, would be the same test to a higher standard, that refers to the HT industry convention of listening to movie playback with peak levels of 105 dB at the listening position, from each speaker. So let's measure it at 1m, 2m, and 4 m for the following use cases: 105 dB at 1m for desktop users, 105 dB at 2m for small room users, and 105 dB at 4m for large room listeners.
That will tell us the approx room size that a speaker will handle while delivering realistic peak levels that are not compressed. And we might find the 305 actually doesn't do so great, even at 1m for desktop use.
cheers