Yes. the Core manufacturers like every other company are constantly trying to reduce costs. They do so by thinning the tube walls, fins, number of fins, thickness of fins, manufacturing techniques etc.
If we do X, it only affect the efficiency by 10% but saves us 5.00 a core. Multiply that by 100,000. Knowing that most systems are capable of handling that 10% loss no one is the wiser. Over a period of say 40 years the above idea is implemented 5 times. The thermal efficiency has now dropped by 50% from it's 1969 design. But now t's 2019 and the majority of the core manufacturers are not paying attention to 1960's radiator cores.
The local radiator shop which is becoming extinct, selects the new core on sizing primarily. The shop also is looking at the cost factor as most customers Aren't aware of the differences just the bottom line on the bill. Ahh this one per that catalog says it the same but is 100.00 or more cheaper. I can put that in my pocket or take it off the bill.
So when we have a big block being cooled by a 22" radiator that has a "NEW" core, it may not cool as efficiently as the original one did.
The cores may appear the same but the thermal efficiency is not and therein lies the root cause.