This is not true - although Elixir's syntax looks familiar, under the hood it is very different; Languages like Ruby are not concurrent, fault-tolerant or distributed in the way that BEAM languages are.
I was actually thinking about this earlier - in Ruby, I would be concerned about app design, for instance, a blog has a post and many comments etc and that is the sort of thing you mostly concern yourself with in languages like that. But in Elixir, you are more of a systems architect - where you think about how the software will work in a distributed environment, concurrently and able to recover from faults and crashes. It's a whole different paradigm
It will become clearer to you as you read more about the language