[mhitza]

I think the reason no one uses shell for anything more complicated is related to the fact that:

1. It's not generally taught in CS classes, and people just search up enough syntax to be able to acomplish their task.

2. A lot of it's variable expansion/substitution are remiscient of Perl.

3. Small mistakes can have huge impact (everyone knows how often rm -rf of unintended directories takes place). Just for the fun of it, I suggest everybody reads at least once the Unix Haters Handbook https://web.mit.edu/~simsong/www/ugh.pdf

If I understood your task correctly, it can be done just nicely in the shell (after all, this is what I think the shell excels at). You'll see the unpleasant side of it when dealing with function arguments and slicing values and referecing specific ones. I don't guarantee it does what you want to the letter, but just my quick interpetration of your description.

    function demo() {
      first=$1
      last="${!#}"

      $first &
      wait

      for f in "${@:2:$#-2}"; do
        $f &
      done
      wait

      $last
    }

    function first() {
      sleep 5
    }

    function pingy() {
      ping -c 8 google.com
    }

    function last() {
      echo -----------------------------
      echo done
    }

    function inception() {
      demo first pingy pingy
    }

    demo first pingy pingy inception last