In an extreme case, someone who doesn't know Java ecosystem might want to stop to research: what is JVM, why is it necessary, which version would be the best, what's the difference between Oracle's Java and OpenJDK, etc...
Out of the top of my head:
- There is the Python 2.7/3.X situation still going on, then there are the several distributions of python.
- GNU's R has a similar problem
- Installing gcc on windows was (perhaps still is) a confusing mess for a newcomer.
IMO I did not find installing clojure any harder than installing Scala for instance, and yet I have never heard (anecdotal, I know) complaining about Scala.
You might not share that users preference of caring about the installation experience of a PL, but arguing that this user's preference is somehow unfair because many other languages also have bad installation experiences makes absolutely no sense.