As long as film contrast responds to development time, the zone system is applicable in full. It may not be as magical as it once was, but it is still useful in the black and white process. (It may even be useful, to a degree, in color, but I don't think this has really been explored enough, especially with today's color negative films.) Aside from the technical process of the ZS, learning it teaches you a lot about how to view the subject. It tells you what your meter is saying, and how to expose based on your measurements. This is applicable to all photography, including color and digital. If you can't compensate in development, it still tells you what to expect and points toward the best compromises.
That said, there have always been great photographers who did not use the ZS.