I feel like Wikipedia kind of glosses over how you might use the Zone System. The idea is that you sample a part of a scene with a spot meter, then use exposure compensation to "place" that part of the scene in a particular zone. I do a lot of B&W film photography, and my go to technique for landscapes is to find the darkest shadow, dial down the compensation to -3 (thus placing the darkest part of the image in Zone II), and then expose the image at that setting.

Digital sensors have different physical properties than film, namely that they clip to pure white rather than clip to pure black. (An overexposed digital picture may have no recoverable detail, while an underexposed film picture may have no recoverable detail. So for digital you want to err on the side of underexposing to capture all the highlight detail, whereas on film you want to err on the side of overexposure to capture shadow detail. Film is somewhat non-linear, too, further favoring overexposure. See also, "reciprocity failure".) So for digital, you aim towards making the brightest object in the scene pure white. You can also skip the zone system and just tune the exposure compensation until the histogram touches the right side. With a spot meter you can practically sample only a few points in the scene; with a digital camera's histogram, you can sample every pixel. Ansel Adams would have enjoyed that.