The Apple HIG says there's a difference between applications and documents. An application might have a bunch of utility windows but those are hidden unless the application is in the foreground. So an application with no open documents running in the background isn't visually cluttering the screen. Application launch tends to be (and definitely used to be twenty years ago) pretty expensive in terms of resources. So leaving an application open without documents tends to make opening new documents faster.
The red button on windows on macOS is meant to convey the action is potentially destructive to the window's contents. Even if the "destruction" of a utility window just means it goes away. It's not tied to quitting the application, with exception of single-window applications like System Preferences, for the above launch cost reasoning.
This has all gotten muddy over the past twenty years. The App Resume/Restore feature in Lion (peak Forstall) is terrible and I disable it on every Mac I use for more than a minute. I can see it being helpful for some people but it breaks the way I expect the system to behave after using Macs for 30+ years.
As a user of Macs since 1984, I love that most apps now save ongoing changes and document state so that I can close most apps and restart them later with the same document reloaded and any changes automatically saved. Documents are closed when I am done with them.
The red button on windows on macOS is meant to convey the action is potentially destructive to the window's contents. Even if the "destruction" of a utility window just means it goes away. It's not tied to quitting the application, with exception of single-window applications like System Preferences, for the above launch cost reasoning.
This has all gotten muddy over the past twenty years. The App Resume/Restore feature in Lion (peak Forstall) is terrible and I disable it on every Mac I use for more than a minute. I can see it being helpful for some people but it breaks the way I expect the system to behave after using Macs for 30+ years.