That doesn't answer my question, though. All of those are reasons to suspect Tor exit nodes, but not reasons to place CAPTCHAs on standard article pages on a si

That doesn't answer my question, though. All of those are reasons to suspect Tor exit nodes, but not reasons to place CAPTCHAs on standard article pages on a site. The only vaguely reasonable one I can see there is 'ad click fraud', and I think that fundamentally restricting the usefulness of a site for advertising purposes is awful.