160 assists was also "impossible" in the 80s and 90s unless your name was Wayne Gretzky.
As recently as a decade ago we had Joe Thornton hitting 92 and 96. In the 80s and 90s, the highest non-Gretzky assist seasons were by Mario Lemieux (114, 98) and Adam Oates (97).
In a world without Gretzky, we would be talking about this topic in terms of Mario Lemieux having one strange fluke season of 114, and the upper boundary of "possible" otherwise being around 100.
Gretzky had seasons of 102, 109, 109, 114, 118, 120, 121, 122, 125, 135, 163. There is more to this picture than just stat inflation.