"People on here" didn't write the article.
IP addresses released have many uses.
Some blocks are almost certainly traceable bevcause they're allocated based on ISP pools for geographic areas. Often, the traceroute of the IP's upstream internet gateway will at least give a city for the individual(s), though even that's a best guess. They are entirely locatable for the ISP/upstream provider assuming you can legally compel them to provide it.
What I assume you mean is that twe say that an individual's IP isn't strictly the legal bar to arrest someone. Because a single IP address can service many people, any of those individuals could've perpertrated the crime. The crime occurs FROM my IP address, but I could have been hacked, exploited, etc.. There's a reason why you don't hear of hackers uploading child porn then calling the police. The bar's too low to presecute without further evidence. Now if they were sex offenders, that's a different story.
And that isn't even getting into the area of illegal tresspass and 'open door' liability that I don't believe have really been solidified in the courts. If a hacker or some random person commits a crime through my insecure or no secuity internet access, am I somehow complicit in the act if I was in fact unknowing it was occurring (TOR for instance)? Where should the bar be set between neglegance and intent?