If you're taking the whole company on an international vacation, or paying to do their laundry and offer daycare, or offering whatever other widely-mocked perk you care to name, it's hard to imagine that worsening employee experience to cut costs is the goal. (Especially when you see open-plan offices even at non-urban companies.)
I think a lot of people really do believe the hype about open plan being better, especially if they're the boss and don't have to actually experience it.
If you can get a community of people who work together to ignore the basic human idea of privacy by cramming people together such that they are forced to live out in the open without privacy, it then becomes easier for them to ignore questions about privacy when creating privacy violating services.
Big successful new companies started out scraping by being built in garages with just a computer, table, chair to use, no private offices. When they grew up they saw no reason to change because it worked for them. So now the company is big and successful and believes that part of its success was the open plan office. So now other companies try to emulate the new young fresh hip fashionable company and so everyone gets open plan, even if its worse than offices.
BUT, why the elaborate dance around that fact? It’s always dressed up as something else? It comes across as a sham explanation when anything but cost is attributed.