How come this person's blog isn't responsive / mobile-friendly? I'm sure that they're capable so I think it might be a choice, but would be interested to hear why.
Responsiveness is one of the more modern (as in wasn't a thing 10 years ago) somewhat advanced parts of webdev and just not in everyone's portfolio of skills. There is a skill level where it's possible to handcode a perfectly functional website, but miss most of the modern best practices.