One commenter on the article has this response:
"However, theatre has a responsibility to be accessible."
Does it? Accessible to whom? This sounds like the argument that Abba are better than Mozart because more people like them. Do Chinese opera and Japanese Noh theatre have a responsibility to be accessible to a Western audience? Does contemporary dance have a responsibility to be accessible to people who've never seen any dance before? Does sculpture have a responsibility to be accessible to people who've never visited an art gallery?
Some works assume a higher degree of cultural capital in their audience than others; that doesn't make it better or worse, just different.