in the '70s there were a lot of studios built without any formal acoustic design. We run into older facilities with tThe types of 'treatments' you describe every once in a while.
I don't know if there was any legitimate reasoning behind this design. The owner may have been trying to duplicate something he'd seen somewhere, or just trying to mix up the walls with absorptive/reflective areas (a common approach). If there is nothing behind the pegboard, it doesn't really serve any purpose. If there is some insulation behind it, it can serve as a type of helmholtz panel for LF absorption depending on the thickness of the pegboard mat, spacing and size of holes and depth of insulated space behind it.
I would say it is most likely a home brewed solution based on very little science and mostly the appearance of what the original builder/owner thought studios 'looked like'.
Carpet offer some absorption at very high freq's only. SOunds like this room, would be a little boomy sounding but if the room proportions were properly chosen it can be treated and made to sound good. I'm gonna guess that the room has odd angles on all the walls, as this was common thinking as a way to avoid 'standing waves' (modes)... All rooms have modes. The non-rectangular rooms are just harder to predict. Taking the walls (and flr/ceiling) out of parallel doesn't eliminate standing waves or modes. It just makes them more difficult to predict.
so... .how does this room sound??