A mixer with sends and returns would be great for instances where you might have a board with a guitar effects chain, and a synth or two and you wanted to be able to send different amounts of signal from each to a single “glue” reverb to make the mix sound more cohesive.
I’m no programmer, but I’m guessing that a mixer with sends and returns and a single reverb or delay plugging would use fewer resources than say three of the same plugin.
It seems like a no-brainer for the MOD!