I agree about usenet, but must admit it’s not very accessible to people unfamiliar with it. I think a good web interface would go a long way to helping adoption. Perhaps one exists and I’m just not aware.
A better idea than a web interface IMO is Usenet access simply built into a browser by default. It makes sense to have Usenet in an email client, because they are closely related, but not many people use email clients any more, so not many people are going to find Usenet that way.
If Firefox had an option to open newsgroups, with proper filtering (not just on the overhead headers, but on the HEAD of each message), I would use it all the time, and I believe many thousands of other people would too.
One part of me believes this would be the best native addon coming from Mozilla in years.
The other part of me worries it would bring on a new age of Eternal September to Usenet, which has been isolated long enough again to form a particular kind of culture that would seem fragile in the face of sudden mass immigration given the size of the Usenet community today.
That should explain at least part of the decision.
Never mind Opera 12 and older.
Could be that we will see Vivaldi revive this, if they ever get that far...
Newsgroups were always bundled with email clients, so Thunderbird has support for NNTP.
It makes sense to have Usenet in an email client,
because they are closely related, but not many people
use email clients any more, so not many people are
going to find Usenet that way.