One could argue that if your text-based forum, which is designed to be read, depends on browser settings and plugins to be readable to a vocal minority of users, then your design is deficient. Many people on HN would make that argument with regards to the need for browsers to have a reader mode.

Ignoring modern web typography standards and keeping the default font size, line spacing and contrast such that it's uncomfortable for many people to read is an anti-feature. Particularly given the only reason it is the way it is is that pg didn't consider it worth caring about.