For experienced Clojure developers this might seem trivial, but new people (in my experience) are very impatient and want to get started ASAP. Honestly, who can blame them? Why does it have to be so difficult in this day and age?
Another thing I hear Clojure developers say is that beginners can start with Lein, but once you get more experienced with Clojure you can switch to tools.build. Why does a build tool need to be so unusable that you can only use it when you become more familiar with the language? You don't see that with Ruby's Bundler, or Elixir's Mix. They just work, just like Lein does.