PopcornTime is just a tool. A tool can be used for both legal and illegal purposes. If a tool user does something illegal with a tool, the user should be prosecuted and not the tool. (The same logic applies to guns.)
Torrent clients are legal though? And prosecution has generally followed the "if a tool isn't advertising 'you can use this to circumvent the law,' it's the user that's liable for an illegal use, not the developer" principle. And as someone who uses youtube-dl to get easy copies of NewsHour... rather annoying that it was shut down.
I agree, but unfortunately the DMCA does not. In order to avoid liability, the tool has to have significant non-infringing uses, and I believe courts will look at how the tool is actually used in the wild as a part of determining that.