The issue is that saying "the economics no longer work" isn't correct because the economics never worked. They traded longterm real value for short term shareholder gains and they're running out of real value runway. It would be more accurate if they said "we can no longer bare the cashing in of our reputation because there is nothing left to cash in".

“Short term shareholder gains” covers a time period of 20+ years?

Amazon is the poster child for the exact opposite of what you claim. They spent two decades plowing every cent into land acquisition, warehouse construction, expanding their labor force, and developing software and hardware.

It was thought impossible to compete with Walmart and others with established logistics networks. Now, they eclipse Walmart because Walmart was focused on the short term, while Amazon was playing to where the ball would be in 20+ years.