No, I'd like to know why he called it 'less reliable'.
He must have used it on nix(linux) or nix(darwin) or NixOS..
The comment wasn't about Nix, it was about ACME clients paired with Nginx being less reliable than having the ACME client built into your server (e.g. how Caddy does it). The comment was by Matt Holt, the author of Caddy.