where did the 70s take the horses

You are absolutely on the right track.

80 something percent of people don't get what you just explained.

Put a 71 motor next to a 72 motor, and there's about 5-10 HP difference if you measure them both on the same scale.

Enter the joker...the 318/5.2 introduced in 92 was rated 230 NET HP.
That's a far cry up from the 230 GROSS HP of 71 and earlier.