This is a fallacy of presuming the market (in this case labor) has to be efficient, and that any irrationalities would be arbitraged away (better employer swoops in and eats Bloomberg's lunch by providing better workspace) and so therefore whatever we do happen to observe must be the rational, efficient, market clearing condition.
This is absurd of course. If true, then literally every aspect of employment in every company would be the 100% optimal condition as expressed via preference negotiation between employers and candidates and there would be no components of working life that are systematically worse off for the employee. Surely you can't be claiming that? If employment is efficient, why are there things like Occupy Wall St? Not that Occupy is right or wrong, but why would it exist? Why wouldn't those companies, with policies people find socially toxic, fail to find enough applicants and be forced to change policies in response to the market?
Their ability to find workers and make money is not very related to whether their practices are unhealthy or destructive, as is the case with open-plan nonsense too.
Why do any market irrationalities persist? Often there is an aspect of market manipulation. In the labor market this can occur by focusing on hiring visa-based workers and using their visa status as discreet leverage to force them to never complain about conditions. Many companies also do actively illegal things, like threaten employees with retaliation if they discuss their salary, in efforts to prevent collective bargaining and depress employee negotiation power over attributes like workspace.
The more disconcerting thing is the way that younger generations of programmers, basically my generation and younger, have been psychologically manipulated into believing that "dynamic" and "collaborative" are synonymous with open-plan, and they are afraid to express any dissatisfaction lest they are downgraded to "not a team player." It breeds what Michael O. Church described as "macho subordination" -- a desire to compete to be seen as most "loyal" by making a public display of willingness to bottomlessly compromise even basic dignity in the work place, so that anyone who stands up for realistic, humanity-affirming conditions is immediately labeled "toxic" and exiled. The workers enacting this don't even know any better, and few of them have had to take a phone call during the work day about a family tragedy, or discuss an awkward medical condition as they schedule a doctor's appointment, or something, and they place low value on such privacy mostly from a position of naïveté.
Anyway, the circular logic of saying markets must be efficient, therefore whatever we observe in markets must be proving their efficiency is patently ridiculous.