Go has been around nearly a decade with the backing of none less than Google and yet it remains a fairly fringe language. Elixir is on a much steeper adoption curve. So is Swift, but Elixir doesn't even have a tech heavyweight behind it.
Marketing.
Pre-1.0 version number would certainly hamper adoption in my $DAYJOB.
Edit: karma_vaccum123 has greatly edited the gp comment but for the record, Google has been using golang since 2007.