Actually it does help.
Part of the ability to calibrate devices (any device for that matter) will depend on the accessories/functionality of the calibration equipment that you have. Fluke multifunction calibrators have several accessories (that are optional) that can enable all kinds of opportunities.
It would be different if one has calibration equipment that outputs the appropriate voltage from the calibrator. As opposed to have something that outputs voltage, then that voltage must be read from a calibrated multimeter source. Same with amperage. One may have a calibrated source that generates a particular amperage accurately. Or, one may have a particular load and the device to be calibrated is connected in parallel with a calibrated amperage device for comparison.
This does not even touch needing to estimate the uncertainties of each verification process.