Gleam is a simple functional programming language which leans into static typing , friendly tooling, and a one-way-to-do-it style. You'd want to use it if you enjoy the programming experience it provides.

It is if you want Erlang but typesafe and with a modern syntax. And why would you want Erlang? Erlang was built for making it easy to build fault-tolerant concurrent applications, for example in telecom.