My two cents...
I find this list to be useful. My experience with Usenet is that there is no way a newsgroup could be as productive.
Consider sci.skeptic. The idea was good, a place where a lot of nonsense like crop circles, UFOs, channelling, etc., could be debunked. Trouble is, there are lots of people who prefer to believe in astrology. They "know" astrology is true through a kind of gnosis. So, out of the goodness of their hearts these true believers invade sci.skeptic, convinced that just by saying the right words, they will bring those heathen skeptics into the light of goodness and truth.
Newsgroups attract their opposites. Sooner or later, the skeptics are gone or drowned out, and the newsgroup is a babel of the nonsense it was supposed to debunk.
Consider alt.humor.jewish (or something like that). It existed for all of two weeks before the neo-nazis invaded it. The neo-nazis believe in all sincerity that if only they tell the Jews just how awful Jews are, they will be convinced of the truth of Nazism.
It's hard to deal with that much ignorance and idiocy. You have no idea how widespread ignorance and idiocy are. I'm an early member of soc.retirement, and one of our principal topics is social security. Most of us defend social security, although a couple of the regulars don't. Because we are older there is a more courtesy than exists in other newsgroups with political themes for dissent.
Even so, we are continually invaded by Red Guards waving quotations from Chairman Peterson as simplified in Forbes, screaming "Ponzi scheme, Ponzi scheme" in our faces. They believe that by telling us what greedy old geezers we are we will instantly be converted to privatization now. It used to be means testing, but the quick fix nowadays is privatization.
The trouble with newsgroups is that the posts are letters to the editor with no editor. lbo is much better off with a mailing list.
However, all that notwithstanding, some of you need to get out there and do battle in the existing newsgroups. It will be battle, but the alternative is to become isolated amongst yourselves. When the ignorance and idiocy get you down, you can find comfort in the mailing list.