Install enough RAM to run every application on your system, simultaneously, without swapping...? I guess there's that.

I am surprised Apple hasn't encouraged users to do that, come to think of it.

For my work laptop, the same ~6–8 apps are always running. No need to quit anything ever.

At home, where I do a wider variety of things (coding, photography, video stuff) I do quit apps, but there's still a baseline of ~2–3 apps (Chrome + Music + one more) that are always running, which I would guess is pretty typical for most users.

Neither Windows nor Android have a (generally-used) concept of quitting an entire application at the user interface level. You can force-quit a process, but that's a rarely-used feature intended primarily for debugging purposes (and accessible through a side-channel; Process Explorer for Windows, app settings for Android). Some applications implement such a concept, but they're generally "single-window" apps, where closing their sole view is equivalent to closing the entire app (games usually fit this category).

Nowadays, you can generally trust your OS to page an app in and out and devote no resources to it if the resources aren't needed. Quitting an app is for misbehaving apps, which isn't assumed to be the common case.