Yeah, it’s a problem with the employment and organizational structure, in a way.

Software doesn’t need continual redesign and redevelopment at constant scale, nor is there unlimited need for new software tools in any one company’s wheelhouse, but the expectation is that software companies hire people and keep them onboard as long as they’re performing well, not that they’ll scale up for a periodic launch and then scale down again. And a company that did that — outside of the video game industry — would be shunned by developers (at least in a good labor market).

I don't think software companies ship UI churn because they're running out of things to do with their development resources. They're just bad at rewarding bug fixing and bad at saying no to user-visible changes that aren't meaningful improvements big enough to overcome the pain of making users re-learn a changed UI. Microsoft doesn't need to scale down their Windows development resources, they just need to make them do the less-fun parts of their jobs instead of shipping new intern project rewrites of Notepad.