There was definitely a lot more junk (mislabeled or fake content, viruses, keyloggers, ...) shared on those networks. Even the Kazaa client itself was riddled with dubious adware. Also legit content was of much poorer quality overall.

Today even public trackers are pretty clean. Cryptominers are trivially caught by Windows Defender. Effective ransomware campaigns are targeted at entities that can pay millions, not random individuals.

They were relatively safe.

In 2000, bad actors couldn't do much with your computer. They could get your computer infected with virus for fun, but that was about it.