Some keyboards and operating systems — iOS is one of them — convert two dashes into an emdash.
I can’t wait for my keyboard to start auto-completing “Your” with “are absolutely right!”
In this case Apple has cared about typography since its very beginning. Steve Jobs obsessed over it. The OS also replaces simple quotes with fancier ones.
I do the same on my websites. It's embedded into my static site generator.
Very related: https://practicaltypography.com/
Agreed that is useful, despite the unintended consequences of dash meddling.