Regardless of the proportion of alleged encounters that are fabricated or genuinely related, the heart of this thread concerns the "rigor" invested in addressing bigfooty claims. The linked paper is held up as an ideal of that rigor, but the analysis therein is actually quite superficial. The authors examined stylized illustrations of "dragons" and visually compared apparent features in the illustrations to known morphology of pterosaurs (to rule them out) and to pieces of several extant creatures (to rule them in, i.e., to speculate on the animals that were used to create the chimaeras apparently depicted in the illustrations).
The premise fails in comparison to what is actually greater rigor regularly on display here and from bigfoot skeptics elsewhere. For example, how would folks rate the rigor invested in the OP paper compared to that invested by folks here on items like the Skookum Cast, Jacobs' Creature, or PGF?
The best bigfoot analogy I can come up with for a direct comparison to the OP would be comparative anatomy speculation leveled against
Myrtle Roe's sketch of the creature her dad William claimed to have seen in 1958. It's an illustration of something someone once claimed to have seen.
From my knowledge of comparative anatomy, I have rejected the hypothesis that Roe saw a pterosaur. But what did he see? Did he see anything at all? Was he hallucinating, yarn-spinning, misidentifying something else, or did he encounter a real bigfoot?
The best we can do to match the rigor we're supposed to be applying is propose parts of the image that might match known animals.
Here's one. I find the thickness and shape of the neck on Roe's bigfoot to look a lot like that of a grizzly bear, and the way the bear in the photo is holding its wrists could be construed as the shape of big, pendulous breasts in profile. The dished face and odd "smile" on the bigfoot are kind of ursid, too.
So IF Roe saw anything at all, I think a decent case can be made that he saw a grizzly bear, misconstrued some things, and let his faulty memory fill in details of things he didn't actually witness.
How's that? Rigorous enough?