The article is plain wrong.
> if every application has it's own language and syntax that is a huge barrier for others coming to work on it
And this is quite obviously not true. A well designed (note the emphasis!) DSL makes any app/problem domain/library/whatever much more accessible than any kind of a "general purpose" language can. Simply because DSL does not obscure the essence of the problem.
> Beyond that you come to issues of code
Code reuse with DSLs is way beyond anything the inferior languages can achieve. I witnessed cases where 30+ years old DSLs got revived by reimplementing them from scratch, immediately making an entire (huge) code base available on a new platform, with new tools and bells and whistles.
> and skill reuse.
One should never care about those pitiful "language" skills. They're worthless.