As to the actual question: Macs have multitasked since my very first one anyway, and that was back in the eighties. Their system-required behaviour was, and still is to leave applications running in the BG until the user expressly Quit them. Closing a window just closed the window—what the cited-site's rabid writer perplexingly referred to as 'minimizing it' (if you speak Mac 'minimizing' means making the window smaller by windowshading it up into its titlebar in days of yore, os shringing it into a postage stamp in the Dock these days). In the olden days of long ago, if you had a bunch of
badly-written apps in the BG, they could gum things up using memory and such. Well-written one just sat there, ready. But OSX does a better job of keeping such things controlled. Not any kind of problem these days.
The real frustration now comes from apps that quit (I understand this is Window's design-behaviour, although I cannot imagine why) when all you did was close their window. Whoever would imagine it was a good thing to wait while the proggy re-loaded all it's caches and other info all over again? Apple's move into a more universal Unix-derived OS has meant the incursion of a good deal of such unpolished, junky, behaviour (requiring filename extensions is another) that to us MacSnobs looks like Windoze crudeness.
So:
…when you X out of a program does it actually close or minimize?
Or do you have to go to the "file > quit PROGRAM" to actually exit the program?
On a Mac you're closing the window,
not the program. If you really want to close the application, the easiest way is the Command-Q key combo (Command being the key with the Apple logo and the cloverleaf) or as you say, using the File menu. But why bother, unless it's a once on a blue-moon app?
Frankly, getting excited about such behavioural differences—like your quoted Mac-basher—is like getting bothered about half the world driving on the other side of the road. Just different, requires some hardware and handware adjustments, neither is superior.