Easier to read than the dials, particulary the tailstock one.
As it is mounted to the moving portions, it iliminates the error from backlash in the leadscrews. Digital scales on their own work fine, but linking them to large screen displays ( DRO )makes life a doddle.
On a mill DRO displays also perform other functions like calculating PCDs etc.
Two axis DRO is a common add on to lathes, but 3 axis is for mills.
If a mill has an additional rotary axis, this becomes the 4th axis.
Personally, I think it's best for a person to learn to use the dials confidently and then only get DRO later as a 'luxury item'
Digital scales and DRO are on my next years Christmas list:biggrin: