A professional medium might have been gate-kept being paying coursework. Perl was not: the super-complete documentation was right there, in the distribution; the remarkably intelligently written course book was right there on everyone's shelves and in your local public library; the in-depth books same thing; And quickly enough even free on the net; the expert-built module library was all there to use and study; the experts were giving their time freely, writing deep dive articles at the simple prompt of worthy questions in addition to columns on topics which I guess were not getting enough questions.

For a professional medium, the only lack that I can tell is from a marketing point of view: installing the distribution for example, probably did not highlight enough how extensive the documentation was.