All hand-held light meters are essentially "dumb" devices. They are designed to do one thing, and one thing only (measure light intensity), but they can do that very well. Hand-held light meters have only one metering cell, and that cell can't see any image, just an average light value. It's just like a bathroom scale, except it's measuring light intensity instead of weight. It has no idea if it's measuring a human or a bucket of nails. Since the 70's, most SLR film cameras had more than one metering cell in the camera. This was done to get more information about the scene that was being photographed, so decisions could be made about how to adjust exposure. For example, center-weighted metering meant that more emphasis was placed on the cell that read the light from the center of the image, rather than the light readings from cells at the outer edges. This made these cameras "smarter" in terms of getting a good exposure more of the time. Into the late 80's, Nikon introduced matrix metering, which brought several metering cells into the camera, which allowed them to use complex algorithms to handle all kinds of scene scenarios to provide even better exposure results. All the other camera manufacturers came up with similar systems. At that time, 35mm cameras were so sophisticated that it would have been a backward step to use a hand-held meter.
Today, with digital cameras, every pixel becomes a metering cell. You literally have millions of metering cells in the camera, and that's how you can get fancy histograms and clipping alerts. That's a physical impossibility with a hand-held meter with a single metering cell.
These days, hand-held meters are still useful for cameras that have no meters (large format cameras, old cameras), or for cameras that have a single meter cell (better light sensitivity and possibly better accuracy with hand-held). Digital, in terms of hand-held light meters, just means that the display output is digital, it still has only a single metering cell. It still can't do anything at all like what a digital camera can do.
In the "old days", pro photographers used Polaroid shots to confirm their exposure was correct, and if not, adjust accordingly. You can do the same thing with a digital camera today, and it's much cheaper than using Polaroid. What you're doing with the digital camera to test exposure, makes perfect sense. By correlating your exposure on the digital camera, with your film camera, you should be able to get good results more easily than with a hand-held meter.
Every hand-held meter is designed to give the appropriate exposure for 18% gray average scenes. That works well for many scenes, but it's the photographer that needs to know when that doesn't apply, and adjust accordingly. The hand-held meter is still "dumb", and can't tell when the scene being shot doesn't meet the "normal" 18% gray average.
