Edit since I'm getting downvotes: All the articles I've seen about the pros and cons of open plan offices mostly focus on productivity. But, as an employee, I'm much more interested in my happiness than my productivity, above a reasonable minimum. These sorts of articles tend to ignore that tradeoff.
This article does discuss happiness somewhat, but the results are less clear than those for productivity. I think it's pretty clearly something people disagree on, but this fact tends to get swept under the rug by authors who focus on the productivity losses.
Having happy employees is a key aspect of running a successful business.
Objective metrics are, by definition, those without subjectivity involved. Naturally there can be disputes over the details, or mistakes made, and through an iterative process errors are identified and corrected, moving arbitrarily close to the objective truth of the situation. Over time, this remedies the problem of individual mistakes and subjectivity being involved in the process.
At this stage, hundreds of studies have been done, so we are well along that path and any remaining errors in the thesis are likely to be minor and non-material.
If this is not true, everyone is welcome to come up with an experiment to falsify them all.
Science evolved precisely as a way to avoid this social noise and find the true status of the subject, through the use of empirical observation and repeatable experiments that test specific hypotheses.
Could there be errors in these studies? Sure, and science has a process for dealing with that possibility, too: create another experiment that empirically falsifies one of their conclusions.
The whole point of the article is that the differences are not inconsequential at all. Numerous academic studies have objectively measured many differences in many different specific environments, and show that the open office is worse in almost all ways related to running a successful business.