I’m from Ecuador. In 2010-2011, in about three months, everyone got the urge to acquire an smartphone, mostly because everyone else was using Whatsapp. After getting to know Elixir, many years later, I finally understood it wasn’t because having Whatsapp meant “free messages” or because you’d get a touch screen; this sudden phenomena happened simply because Whatsapp never broke. You could lose your connection, but you’d get your messages back; a single conversation could misfire, but “the system” was always on; it didn’t matter if you were 4000 mts high or in a little village in the jungle: you could rely on it. You could rely on it more than in SMSs. This same thing happened worldwide. There were obviously brilliant people involved, but I do believe a lot of Whatsapp’s success is due to Erlang.

(I assume both references pop up frequently, but they’re quite interesting anyway)

Why WhatsApp Only Needs 50 Engineers for Its 900M Users

Erlang Factory 2014 - That’s ‘Billion’ with a ‘B’: Scaling to the Next Level at WhatsApp
https://www.youtube.com/watch?v=c12cYAUTXXs

fb is a different thing and I personally think we shouldn’t try to repeat in any language

They both compile to BEAM bytecode, and Elixir essentially evaluates to the same Erlang code, so no.

You mention Telegram, Whatsapp or FB as example of scale. Discord is using Elixir and it’s massive.

Well considering WhatsApp is written in erlang it would certainly be doable in elixir as well, elixir and Erlang have nearly identical characteristics being based on the same VM.