The script even installs docker with apt by itself (which, I think, is the only reason they require Ubuntu as the OS -- to not to deal with any other package manager variants)... I mean, why? Just let people install docker however they like! If you don't even trust your users to install a container runtime, who's your target audience really?

It's also over complicated, like, it even tries to handle race condition of multiple apt processes! What kind of environment do they expect the users have? As the project become more popular, the script will need to handle more edge cases. Let's see if it is still a 5 minutes read one year later.

> I guess the shellscript is for people who want a one-line install, which I wouldn't do myself either, but I guess some people prefer.

This is the problem in lots open source projects -- providing a one-liner installer and bragging about how easy the initial setup is, without an easy path for long term maintenance. Give it some time, many happy users of the one-liner will be unhappy when they encounter issues.