NZB - Newsbin

[Scott]

You don't hear about that many torrent sites being taken down, several have been blocked but if anything that has increased their popularity.

I wonder why those sites remain open but the news groups close down?

There's been a steady stream of them being taken down over the last few years, some of them high profile, some of them not so much. It's not newsgroups closing down, it's the sites that index NZBs. Binaries are still available on newsgroup servers until the server provider receives a DMCA request.