Where you read that? can you provide any source?
You can read about this (they're not wrong) just by using your favorite search engine. Here's one such article from a reputable source:
Honeypot reveals mass surveillance of BitTorrent downloaders
Within 3 hours of downloading, the copyright enforcers likely have your IP address, according to researchers who put a fake pirate server online and then sat back to see who came sniffing around.
nakedsecurity.sophos.com
They've been doing this since the Napster days.
In at least one instance, the copyright claim was invalidated 'cause the owners of the copyrighted material posted it themselves and then ran around filing copyright infringement claims.
If you want to do a deep dive, look at New York Country Lawyer on Slashdot, though much of that is likely 'ancient' by modern standards. I'm not sure what he's doing now, but it's probably still fighting copyright infringement cases. I suspect you can find some EFF articles on the subject, if you did deep enough.
(EFF is one of my favorite organizations. They get a monthly donation and other donations throughout the year.)