More specifically, people started using copyright infringement lawsuits as a business model.
It took years for the courts to discover that, say, Prenda Law weren't just some lawyers trying to stem the tide of rampant BitTorrent piracy, but were actually sharing their own content and then suing people who downloaded it to make money off of settlement demands. However, now that this has happened, it's significantly harder to get out-of-order discovery on a John Doe just by alleging an IP address sent parts of a file. Courts want something more than that.
AFAIK the big thing nowadays is abusing Florida's "pure bill of discovery" to subpoena people for copyright litigation. This is legally dubious because copyright is inherently a "federal question", meaning that state courts aren't supposed to touch anything even remotely related to it. However I haven't yet seen someone try and attack otherwise valid copyright cases based on the fact that early discovery was improperly granted.
My personal opinion is that Congress needs to step up to the plate next and realize that individual filesharing does not cause nearly as much harm to copyright owners as the law currently presumes. Statutory damages should not be available when suing people who merely shared infringing files for non-commercial purposes. Allege a direct commercial benefit or hope you can prove actual damages.