This is not a CSS framework, this is a stylesheet you import when you don’t want to think about CSS or styling but want a site that looks alright.
Some people aren't specialized in front-end (or they just find it boring) so they're more the target audience. I did this because I wanted to avoid having to redo an UI each time I started a new hobby project
While there are customization options, it's really intended as just being an include without the need of changing anything else in your documents