I think the people behind those clients were clear targets back in the day, before the advent of services like Netflix and Spotify alleviated some of the financial troubles experienced by the entertainment industry.

KaZaA for example (which became Skype indirectly)

After making it repeatedly clear that you think Bittorrent is the next big thing for pedos and that your client is intentionally optimized to keep pedos safe from the government.

Nearly every time someone gets arrested for developing software they where also advertising and in some cases outright advising people on how to get away with illegal shit using their software.