Just to add, Vista’s biggest change broke compatibility with so many applications with the implementation of User Access Control (UAC).
While it was a long-overdue feature for security, lots of older applications would either fail to install or not work properly because it expected to have full system access with no roadblocks. While there was compatibility mode, the results were still very much hit or miss.
Then there was the massive headache around the original implementation of UAC which would constantly go off, usually multiple times during a software installation and again when starting some applications. Most people would’ve turned off UAC because of how annoying it was.
Usually the systems that need to be modernized are working, so nobody wants to invest in a new system that may require retraining the people that may be impacted. Then there’s some systems with integrations that may also require replacing so the integrations can continue to work.
Even then, there’s always a good possibility that the automation fails, especially in the first few iterations of trying to sort out the kinks, and third party automation tools aren’t perfect either. That’s another tool to have to update and maintain once all is said and done.
I’m not trying to rail too hard against the changes, but the impact is especially felt by the people managing the systems, who’s most likely getting more work tacked on to their workload of putting out fires behind the scenes.