[bennyp101]

Yea, Credo[1], one of the static analysis tools for Elixir specifies it as:

  Numbers can contain underscores for readability purposes.
  These do not affect the value of the number, but can help read large numbers
  more easily.

      141592654 # how large is this number?

      141_592_654 # ah, it's in the hundreds of millions!

  Like all `Readability` issues, this one is not a technical concern.
  But you can improve the odds of others reading and liking your code by making
  it easier to follow.

Should make it more obvious that it is purely a readability thing, and that is obviously subjective anyway

[1] https://github.com/rrrene/credo/blob/master/lib/credo/check/...