The issue with your arugment is that you are looking at it from a "cost" perspective only. Companies have a lot more problems to worry about. Local laws, regulations, is everyone cut out to be able to work remote ? etc etc. In the US, you also have to deal with shit load of laws state wise. For most companies that don't have the pockets of FAAANgs or well funded companies, it is just not viable to go "fully remote anywhere". It sounds exciting but logistically it is not that simple.
Also, you cannot just assume that just because the company decided to cut salaries by 40%, everyone will be excited to pack their bags and move to say "Kansas" or "Idaho" or wherever in the world. Not everyone wants to be a nomad. Lot of us like the stability of a home, a city where we live and have made friends/family and many other reasons. If that was the case, I am sure a lot more people would be moving out of NYC/LA/SF already. Not the case.
I say this as a small bootstrapped founder who has team members in 3 countries and we are only 15 or so. Remote teams are NOT easy. Not at all. I personally would love everyone to be able to work together in 1 office and call it a day. Yes, I am all up for flexibility to work remotely if needed from time to time. I just don't want to deal with the hassles I explained in my first paragraph.
Finally, lets say that we do look at it purely from a cost perspective. On an average, a "good enough" engineer in India will always be at least 10x cheaper than a good enough engineer ANYWHERE in America. It is just the facts of how the global world is. Don't compete on cost. You cannot beat that. Compete on other things.