I think what you're talking about is how on Mac, an application can stay running without having any windows. Separate from closing all the windows, you usually have to "Quit" the application if you really want it gone. This is useful for a couple reasons:

- You can "Quit" the application without closing all the windows, and then the next time you start the application, your windows can come back.

- You can close all the windows without "Quit"ting the application, and you don't have to wait for the application to load again in order to open a window later.

Additionally, since application lifecycle is managed separately from the open windows, apps can do cool things like saving and restoring the set of open windows through a system restart. Which Windows and Linux still haven't managed. (Maybe Windows can try to restart the processes... I think I saw that becoming an option more recently)

I've never rebooted often in general, even when I daily-drove Windows. Then, it was because it was annoying to get my preferred workspace back after a Windows restart. Now, I daily-drive macOS and I don't often reboot until the machine gets slow/janky because the machine doesn't really need a reboot until then. And I don't hate reboots as much as I would for Windows because macOS is a lot better at session restoration