There's plenty, but they don't have enough material to post once a week. And if you don't post once a week, you don't end up on HN once a month. As simple as that. Looking at the blogs that show up on HN regularly, the usual hit rate is 10-25%.
The problem is that Zitron has charm, an authoritative voice and a very aggressive online presence. That's a difficult combination to compete against.
The landscape has changed a lot, but his content has remained mostly the same, maybe much more aggressive and less curious (in the beginning he would entertain other viewpoints more often), but since the tech itself has changed around him, so his repetive shtick falls a lot more flat than it used to because he is completely unwilling to entertain any other position other than the one that established his blog/show.