The simple explanation: It's an arch based OS that has many DE options and focuses on building Linux knowledge.
For the super complete explanation you can check out their site. They have a several step program to kind of ease people into building their own set up.
Personally, I'm not using it in order to do their learning process. I was looking for an arch based system with good reviews that had a nicely pre-configured i3. So far so good 😀
Linux geeks doing what Linux geeks do...