It isn’t perfect but it works. That’s the only ID used for our 100% vote by mail system in WA. Even when there’s a problem it can be quickly resolved. In the last Dem primary in 2020, my wife got a notice that her signature on the mail-in ballot didn’t match the one on file from 20 years ago when we first moved here. The election board just sent her a form for a new signature, she signed it and mailed it back, and done.
There is a built-in safeguard with VBM systems in having voter registrations linked to current address, so you’ll only be able to correct a signature mismatch if you actually live at the registered address to receive the correction form.
Any other form of ID is unnecessarily complicated, but it will take years to get this changed in the more backward states.