This is a little bit of a bigger deal than the headline is indicating. Legally, it was decided a while ago that IP addresses can’t be linked to a single user in most (but not necessarily all) cases. That’s not new.
What is new is that the accused got the case dismissed with prejudice and is having his court costs reimbursed. That is a big deal. In plain english, that’s the court telling the accuser (the copyright holder), “get the fuck out. Don’t ever come back, and while you’re at it, pay the defendant $17k to cover his costs.”
Now all the copyright holders have to do the algebra to determine if it is worth it to take people to court, if there is a nontrivial risk that the copyright holder might get bitchslapped and forced to shell out ~$10Ks in the defendant’s legal fees. This case specifically is only relevant in
Oregon the 9th Fed Cir (EDIT: this was 9th FedCir, so its a much broader ruling. I read too fast and thought this was a state case); however, the ‘informal’ precedent is out there now, which can have an impact.