depending on the mixer, you get other benefits ... like mix automation, MMC control, surround panning, comps/gates on every channel, etc...
You can also do this kind of stuff with external gear .... but I find that it comes standard (or as an option) on a lot of digital mixers.
Plus the avoidance of additional D/A A/D conversions helps. But ... all my verbs are analog, so I have to convert to get the signal to them ... and then convert to get it back. However, once I capture a sound with a mic ... the signal is digital until it plays back thru the monitors. Which, I think, goes a long way quality-wise.