I actually have a theory, based on the last episode of the 2.5 admins podcast. Try spinning up a MediaWiki site. I have a feeling that wiki installation are being targeted to a much higher degree. You could also do a Git repo of some sort. Either two could give the impression that content is changed frequently.
yep, I'm running a pretty sizeable game Wiki and it's being scraped to hell with very specific urls that pretty much guarantees cache busting. (usually revision ids and diffs)
I could believe that. Plus, because both of those are more dynamic, they're going to have to do more work per request anyway, meaning the effects of scraping are exacerbated.