The reason is because Go is very popular where Elixir is not, if Elixir was standing where Go is now it would be pretty much the same, I guaranty you that.
As for the reason why it has less complains it's pretty simple no one uses Erlang and it's a niche, it's not a generic purpose language. I can't even tell a single known application or library written in Erlang.
To my knowledge Ericsson still writes most things in Erlang. Yahoo uses it for a couple large services. My company use PagerDuty which is also written on BEAM.
I'm sure there are many, many other things in not familiar with, but claims of Erlang's demise are greatly exaggerated.