Well, on a lot of the stuff I repair, you can see the soya-based stuff gets destroyed, not just by mice and rats but it gets white stuff on and then goes brittle and crumbly.
Meanwhile with the exception of wires in high-temperature areas, PVC just doesn't do that.
The thing to understand about the soy stuff is that the soy part gets completely reformed chemically into a polymer, it's not anything food-like by the time it becomes part of the plastic.
Aside from that ... this is not an anecdote vs anecdote debate, these wires have been around for decades and this exact question has been studied scientifically. The degradation rate and wire-chewing prevalence are comparable with PVC.
Now you're conflating rodent chewing and other degradation. That just increases my suspicion that there's confirmation bias going on.
Notice how in my first comment I said "highly biodegradable"? It's just a couple of posts above this one. In fact here you go, have a permalink:
https://news.ycombinator.com/item?id=50185779