I think 4 could be a legitimate concern - if there are no good resources for you to learn from, you don't want to accidentally put your company into a position

I think 4 could be a legitimate concern - if there are no good resources for you to learn from, you don't want to accidentally put your company into a position where you have an unmaintainable code base because of a "known unknown". However these days we have the wonderful open source code being put out by the Basho people as a useful guide, so it's no longer a problem with Erlang.