I have 14 windows open, currently. That's not hugely unreasonable to display in a window switcher … not to mention that every other OS manages it? I've had more, but I mean, how many more are we even talking?
(And if you have a huge number more open, well, how does exposé function?)
And the window switcher on other OSes usually orders the choices by Z-order, which is essentially in recently-used order. The window you want is often only one or two hits away.
(And, if not, the one in MATE in Linux is also navigable by arrow keys or by mouse, so nothing's too far away.)
How many windows do you have opened? How many things are you doing at the same time?
Is this because you lose configuration if you close them, or because they take too long to open? Because you can't really use so many of them to make switching not viable on a single virtual desktop.
I tend to have a ton of apps/windows open at any given time due to a combination of tasks often requiring a fairly wide array of apps, but also to reduce the friction of context switching to a minimum (even with a lightning fast SSD, closing one set of apps/documents and opening another takes time). So at any given time I probably have apps/windows open for a few different tasks open.
Virtual desktops get heavy usage from me, but (Cmd|Alt)-Tab switching being caged off per-desktop would actually pose a problem, because when I reach for an app with that shortcut I'm not actively thinking about which desktop it's on — I just want to go to it, wherever it happens to be, even if it's been intentionally placed on a particular virtual desktop.
So app-scoped Cmd-Tab works well for me, because the number of entries it has is always reasonable to tap through and it includes entries from all desktops on both screens.
(And if you have a huge number more open, well, how does exposé function?)
And the window switcher on other OSes usually orders the choices by Z-order, which is essentially in recently-used order. The window you want is often only one or two hits away.
(And, if not, the one in MATE in Linux is also navigable by arrow keys or by mouse, so nothing's too far away.)