As a programmer, you sometimes want to make an alphabet lookup table. So, something like:

  var alpha_lu = "abcdefghijklmnopqrstuvwxyz";

Typing it out by hand is error prone as it's not easy to see if you've swapped the order or missed a character.

I've needed the alphabet string or lookup rarely, but I have needed it before. Some applications could include making your own UUID function, making a small random naming scheme, associating small categorical numbers to letters, etc.

The author of article mentioned they do web development, so it's not hard to imagine they've had to create a URL shortener, maybe more than once. So, for example, creating a small name could look like:

  function small_name(len) {
    let a = "abcdefghijklmnopqrstuvwxyz",
        v = [];
    for (let i=0; i<len; i++) {
      v.push( a[ Math.floor( Math.random()*a.length ) ] );
    }
    return v.join("");
  }
  //...
  small_name(5); // e.g. "pfsor"

Dealing with strings, dealing with hashes, random names, etc., one could imagine needing to do functions like this, or functions that are adjacent to these types of tasks, at least once a month.

Just a guess on my part though.