I honestly don't buy this explanation because it doesn't make a lot of sense to me. What vintage components are so special that they cannot be substituted with a modern equivalent? We're talking about resistors, capacitors, pots, silicon and wire. I remember Steven Fryette saying an interview recently that his theory as to why Mesa would come up with excuses to not remake the IIC+ is because it wouldn't be a profitable venture from a buisiness standpoint. The high grade of steel required for the transformers, which was cheap in the 80s, grew in cost over time to the point where it was too expensive or rare to mass manufacture. Very little if any profit margin.
I have heard on good authority that Randall was always a little bitter about the C+ because it wasn’t his entirely his baby