A spot meter alone, without adequate knowledge on how it works and/or how it sees the world can be a dangerous thing in some one's hands. With the power of a spot meter....they have the ability to ruin many photographs. [[ Personally, I think this speaks to the fact that the price for joining the "professional photographer's cohort" should involve an entrance exam. Similar to the PPA craftsman and master-photographer designations (not even sure if they still do those or not). Those tests were hard, long and involved a lot of knowledge that jo-sixpack and socker-mom-sally just didnt have the time to learn.]] Same thing on the inner workings of a spot meter...dont use it unless you know how.
Meh- We all could complain about the state of affairs with everyone owning a camera now a days.
I think that its great that you have found the ZS and are preaching its message to all that will listen!
The ZS is great in the darkroom because it was an entire method of sensetomitry. Running true speed film tests, plotting your own response curves, keeping meticulous notes about how you mix chemistry, with what water, and at what temperatures with which manufacturer's run of a specific developer etc etc.... ad infinitum.
The ideas of previsualization and the breaking up the tonal scale into zones is only a small portion of the process. The relationships between highlights and shadows (contrast) in a scene will not change if your meter isnt calibrated (see: K factor, or the built in manufacture's bias that is built into every meter ), but what your meter, digital or analog, thinks is ISO/ASA 100 may not be the same sensitivity ISO/ASA that your camera wants. I have seen exposure graphs of meters vs digital sensors vary significantly depending on the manufacturer. There are automated calibration methods out there, such as those offered by sekonic to calibrate their higher end handheld meters. These involve using a stepped zone scale calibration target and software with algorithms that evaluate the target and create a metering profile for your specific sensor. Sekonic's DR-758 can store and utilize up to 3 different camera sensor/film response profiles for metering.
All that calibration and metering so that your meter can see a scene and it say "I need X amount of Lux/FootCandles/EV" and your camera say "Give me X amount of Lux/FootCandles/EV"....everyone is happy and on the same highly calibrated page. :-p
Even with digital tech on our side, there are still variables to overcome if you are looking for a more "ZoneSystem" like precision.