I think the problem is that there is Erlang, the syntax, then Erlang, the features, and then there's OTP. It's a bit much all in one if you might have not done FP before, and then only with C-like syntax languages (e.g. Java).

When I joined an Erlang project I also had some aha moments with the syntax and how stuff is structured, and I found Elixir much nicer to work with (without any real Ruby experience). I don't want to say Erlang is not modern enough, but some things felt like they were around half the work (and more enjoyable) with some Elixir libraries (vastly bigger ecosystem than pure Erlang), for example handling XML.

It might be a bit simplistic, but I don't think you really lose anything meaningful when using Gleam or Elixir over pure Erlang. Just like you don't lose anything when using Clojure or Kotlin over pure Java.