Still, for application developers the idea of installing "system-wide libraries" is all but gone. An application installer will just install to \Programs and that's normally it, even for very large applications (Obviously something system-y like a driver still installs system files). Even things that used to be typical system things like runtimes (C++, .NET) can now be locally deployed, which is nice.
In the 90's it wasn't uncommon for installers to just poop application files or config files into Windows\System32.
