The comparison comes because they're trying to draw conclusions about the effects of large sauropods on the prehistoric environment from modern experience with mechanized agriculture.
"As the total weight of modern harvesters is now approaching that of the largest animals that walked Earth, the sauropods, a paradox emerges of potential prehistoric subsoil compaction. We hypothesize that unconstrained roaming of sauropods would have had similar adverse effects on land productivity as modern farm vehicles, suggesting that ecological strategies for reducing subsoil compaction, including fixed foraging trails, must have guided these prehistoric giants."
This is strange because the subsoil composition of today vs. 65+ million years ago, let alone 250 million years ago, is substantially different. Mostly different insects, different bacteria, and though Earthworms did exist for much of that period, other types of worms did not. Lignin was already in trees and mushrooms were already in the ground, but soil as a living ecosystem was far less developed and alive than it is today - it was probably closer to regolith at least in the 250-100 million year ago period.
"As the total weight of modern harvesters is now approaching that of the largest animals that walked Earth, the sauropods, a paradox emerges of potential prehistoric subsoil compaction. We hypothesize that unconstrained roaming of sauropods would have had similar adverse effects on land productivity as modern farm vehicles, suggesting that ecological strategies for reducing subsoil compaction, including fixed foraging trails, must have guided these prehistoric giants."