People who make horror games with the intention of drawing an audience usually happens outside of the FVN community. As far as I can tell, no FVN that was made to please an audience are horror. It just so happened that the of the horror FVNs we have, a good portion of them became some of the most well known ones, like Echo and all the other VNs within its continuity, and Burrows.
And yeah, that is a good point I implied in the blog. If you look at Patreon as a service rather than a way to support your audience, it can be a bit flimsy and just buying it with a single purchase is a better value. Still, both have their own functions and Paid games are gated towards people who can't pay while free games (that are funded through Patreon) aren't. So there are reasons for either.