Engines become better, maybe true but have you noticed what current exhausts and (conical) manifolds can do with older engines ?
3 years ago I did get a Nova-2000/8p new in box, it was by then about 12/13 years old.
I did run this engine and people who thinks they needs the newest engines go go fast and still I was faster than them and I did run the same laptimes as with a JP R01 but I was running on the 2015 exhaust, one of the best by then. This engine was a square stroke and had no multy exhaust and it seems it was not needed.
Imo the devellopment of manifolds and exhausts did do more to the performance than the engine itself.

Yes, cars are onder changes too but trough the years they are driving much easyer and are not critical anymore to find the sweet spot.