I looked all over their website, but could’t find a link to download the source for the Wolfram Language so I can compile it. Do you have a link?
EDIT: One common exception to this principle is the use of proprietary C or Fortran compilers for high performance.
The blog post was probably literally written in and hosted entirely on open source software which were highly innovative at their earlier stages and continue to be highly innovative. This is a very self-serving presentation of an idea. Also, I officially dislike the word innovation.
Why don't you answer the question?