I consider the premise to be flawed, as the evidence is not as the premise summarizes. We kept a thread going for months that pulled in scores of examples of tree manipulations, structures and other "stuff" that is difficult to explain otherwise. Moreover, there have been many accounts of these things in the context of a Class A sighting, a number of eyewitnesses to contemporaneous creation, and at least one or two witnesses to the actual creation of them.
I also disagree with the premise that these structures are easily explained as being caused by natural forces/occurrences. That is a handy thought stopper, but when pressed to explain something truly extraordinary and puzzling, and are asked to give the mechanical details of how something like this could be formed, they wave their hands and mumble "ice storm, snow storm, wind...." As if those wouldn't be the first things any rational person would consider and rule out. Plenty of what you encounter in the woods is the result of natural processes, and many of the things attributed to Sasquatch manipulations undoubtedly are too. What that leaves you with though are the tougher nuts to crack and unless you can plausibly say, "THIS was caused by THIS, and this is HOW", you have as much uncertainty as the rest of us and you are going to lack a definitive explanation. For those things in that last category, the choice narrows down to "Something very strong, with a big reach, and with hands". The long list of possible causes, at that point, only has one candidate on it.