The FBI is just sending a message. They cherry picked a few IP addresses, set surveillance on them, and then chose those few which belonged to people who were

The FBI is just sending a message. They cherry picked a few IP addresses, set surveillance on them, and then chose those few which belonged to people who were active on forums revealing that they were in fact probably guilty and didn't just have a trojan or little brother. If the FBI intended to comprehensively prosecute every offender your point would be a genuine hindrance. However they only need a few to deter the behaviour and they know this. Thousands of people participated in these protests, and a handful are going to be made examples of. It's not at all unlike a flesh-and-blood protest.