If you are very old[tm] you might remember that github pages were hosted on USER.github.com and they moved to USER.github.io in 2013, https://github.blog/news-insights/product-news/new-github-pa...

JFTR, I also think they could at least have used a couple of pronouncable domains, or put stuff under a .github.io domain, or at least make it githubrepo.com or something not acronym-y