Can't believe I'm still subscribed to this lol.
NZBFinder sent out a newsletter about this recently, and since it makes sense, I thought I'd pass it on. I have no other sources so take it as you wish.
"You may have noticed a rapid decline in content being available on Usenet over the past few months. Due to automated DMCA takedowns etc. a lot of posters have resorted to obfuscating their posts in such a way that only a select few indexers know what they are. You will see most free or smaller (even some bigger) indexers fail in the next few weeks and months and some may have already failed to bring you good content quickly.
Luckily the staff here at NZB Finder has been working hard to keep bringing you the best Usenet has to offer. You've probably seen the number of releases on NZB Finder shoot up tenfold in the past few weeks due to our work. A lot of very high quality stuff like more REMUX, WEB-DL and complete BluRays have been indexed."
So it sounds like it's fairly indexer dependent. I use about 30 different index services with SickRage so I don't notice it, but I could see if you were only using primarily one or two indexers this could be a big problem.