You are missing the point. The author is satirizing the fact that there are so many tools and patterns that do basically the same thing. The author doesn’t want to bother figuring out what installation method this particular tool recommends. So they have this script so that he can run geterinstalled inkscape and let the computer figure out which one works.
If you were going to write geterinstalled pip foo you may as well just run pip install foo.
Also note the title-text, which addresses this exact issue:
The failures usually don’t hurt anything, and if it installs several versions, it increases the chance that one of them is right. […]