[bsder]

> the tracks each pass through their own DAC connected to this old-school analogue summing mixer, and then are re-recorded on the other side. It seems totally foreign to me

There was, at one point, good reason for doing this. Digital summing is really easy to get very wrong. ProTools used to introduce some really nasty artifacts back in the 16-bit days if you had non-linear effects.

24-bit chains have made a lot of this moot. And using 32-bit float as intermediate calculation steps makes even more of it moot. And, increased computer power ... etc.

Then there is the always present "Magic Box X adds tonal coloring that I like." You can't actually argue against this very well unless the box really doesn't do anything at all.