I think models using these harnesses were also RLHF'd hard on responding to looping instructions and following through on goals. Older models were tuned for basic chat responses.
It's more like we just invented ball bearings. We just jumped from standard to industrial grade, and precision grade is on the horizon. All kinds of new possibilities have opened up, cars can go a mile a minute on these things! Surely if we keep increasing the precision at this rate, we'll defeat friction once and for all.
One could use gpt-4 or gpt-5 with today's harnesses and we'd see how well that goes.