In the end of the day everything is subjective. A choice of what objective measuremetns to make is already a choice.
I think the reason for their list not having that 9.0 monitor is that it is 50% more expensive, and doesn't really add that much more. One might say it is superfluous. They should probably add their justification to the article though. Personally I am in agreement, I wouldn't buy a 5k display for my office staff because I really don't think it adds anything over the 4k display to their productivity, but I could definetly justify a 4k display over a 1080p display.
I think the reason for their list not having that 9.0 monitor is that it is 50% more expensive, and doesn't really add that much more. One might say it is superfluous. They should probably add their justification to the article though. Personally I am in agreement, I wouldn't buy a 5k display for my office staff because I really don't think it adds anything over the 4k display to their productivity, but I could definetly justify a 4k display over a 1080p display.