It's not just Substack. Here are news sources for Republicans and Democrats.

Republicans don't really pay attention to any serious written publications. Even The Wall Street Journal is more likely to be read by Democrats.

This isn't a media bias issue. Conservatives have seen media startups: see the rise in Tucker Carlson, Candace Owens, Breitbart, and Newsmax.

They're just all trash. The conservative audience wants conspiracy theories and Trump worship.

I enjoy City Journal, but its readership is small, reflecting that the high IQ, intellectually curious right-leaning audience is extremely small.

No one is stopping rightists from starting a Vox, or Atlantic, or New York Times. The conservative audience just isn't smart enough for it.