Even if they were in the top 10, I bet the average HNer would struggle to name 10 distros.
You are right that the distrowatch.com page rankings are fairly divorced from other measures of popularity: MX Linux, (apparently a Debian fork by the antiX people) sits at #1 and there are 3 Arch forks above Arch itself, which doesn't manage to crack the top 20.
You are right that the distrowatch.com page rankings are fairly divorced from other measures of popularity: MX Linux, (apparently a Debian fork by the antiX people) sits at #1 and there are 3 Arch forks above Arch itself, which doesn't manage to crack the top 20.