Thanks. The idea is to make it easy to do continuous integration testing of Arduino projects specifically so that people with only a few libraries would start doing CI.
When I started with the project, the process of using the Arduino IDE in a Travis CI build was more complicated than it is with the recent IDE versions. I wanted something that would allow me to always use the newest version of the Arduino IDE in my tests without having to go update 20 repositories every time there was a new IDE release. I also wanted to make it easy to test with multiple IDE versions to ensure backwards compatibility. I found there are issues with certain versions of the Arduino IDE that can cause a tremendous amount of confusion for someone trying to set up a CI build configuration from scratch using that version. The script attempts to handle all these issues seamlessly, without exposing the user to any of that complexity.
Over time, I've added more features to the script, each adding to the length of the documentation. For this reason, it may now seem a bit intimidating to a potential user. I think I could improve on this situation by providing links to demonstrations of the basic use of the script for a library and a sketch. I actually do have a link to the .travis.yml file of one of my libraries for this purpose, but I have added other tests to that file over time so that it no longer serves well as a simple demonstration of arduino-ci-script. I need to create some dedicated repositories for that purpose.