As you hint, incredible demand for full stack developers created high salaries at businesses that viewed that as their core product. Businesses that built things that had software mostly kept paying what they always had. That voracious demand seemed to feed on itself a bit and grow on its own. When times got rough those businesses asked themselves if they were getting the expected roi on all those positions, and if they could be more efficient and do almost as well with fewer heads. They apparently decided they could. I don't find that surprising, software isn't infinitely improvable. Once you have a product done and refined, there simply becomes less to do over time. If the hours spent maintaining a site never decrease from initial development levels, you are doing something wrong.