On GitHub pages you can generate static content for blog using Jekyll (or similar). The problem is that for every change you make to a file, a full recompiling is needed. Plus, you need to have locally installed git client, ruby and jekyll related software. When you need to do some changes on fly to some articles and you have not all the software installed (for example if you are using your mobile phone or you are in an internet-cafe) it is a sort of problem. Is there any platform that allows you to generate static-content-blog on site?
You actually don't need a locally installed git client for Jekyll to run, since github pages will actually do the compilation for you every 10-15seconds from my experience. The only reason you need a local client for Jekyll is if you are doing theme-type development, which requires git, and ruby packages.
If your just adding new post articles then you should be using prose.IO to add files into the posts folder. That automatically will generate static files through github pages using jekyll
If you used another site generator like Hugo,Ruhoh, Hexo, etc you WILL need a local dev environment though as github doesn't support compilation through the server for this, Jekyll is the only one that doesn't require this
IF you wanted to do edits + blog posts on your phone at a cafe, you can do it through the desktop version of github while on your phone. It isn't pretty or optimal, you really should be using a laptop while making posts