There was a whole family of stackable instruments from Siemens. These have a GPIB connector on top and bottom side, and there was a base module that brought out the GPIB to the back side. All of those were intended purely for use in ATE, having no local user interface. I did pick up a DMM from that series at some time but have sold it in the mean time.
It did make a lot of sense, you will understand when you see how a typical GPIB wired test system of 10+ devices looks like on the back side. Sadly, as so many good ideas, it wasnt widely adopted.
Would have been nice if the semi-standard 1/2 19" and 19" format would have adopted a similar solution.
It is now getting better with more recent interfaces with thinner cables, but GPIB spaghetti was a very real problem for many years.