If everyone is remote, why not put your employees in Costa Rica? Or São Paulo? Colombia? Heck, even Canada is cheaper than many places in the US.
And we're only talking about timezone-aligned markets. You can also consider Poland, or India, and now you can hire a lot more resources for the same cost. Sure, it will be less efficient, collaboration tax and all, but 2.5X is quite a difference.
The one thing holding US-based companies from going all-in offshore is the belief that in-person relationships still matter. They would rather pay the extra COL mark up than save 40-70% for a remote employee.
To be clear: the jobs are going to other markets; this is not a either or situation. But at least hybrid RTO has as a dampening effect, and protects the internal job market. We should be celebrating folks like Amazon, not complaining that they don't get it.
In the past we had more demand than supply, which kept salaries stable (read: high). Now there's more supply than demand, and the main thing holding salaries stable is that employers still want warm bodies walking through their doors every day. Remove that, and you get a race to the bottom.