Yes it also quotes the phrase “Police have a duty to pursue all reasonable lines of enquiry,”.

Who's judging what's reasonable here? What stops them making requests victims would rightfully consider unreasonable so the police can just claim that the victim was uncooperative so it doesn't negatively impact police statistics?

I guess that they're raised the bar on "cooperative". So if you've been the victim of a crime, you can't report it if there's any evidence of totally unrelated crimes. Say that you were raped, but had also ordered illegal drugs from your phone.