Exactly.

That's not direct nepotism, but it's kind of a 'once you're in, we'll take you rather than risk somebody new' kind of mentality, that further keeps the arts closed off.

Also, a final dimension to add to the OP discussion, is that many arts students now have to be willing to understake years and years of 'internship' work before they 'make it', so unless you have a rich mum and dad willing to pay for you to keep working for a loss in small productions, you can't really manage it anymore.

Working a small job AND becoming a successful actor increasingly doesn't work in modern economies like it used to when many could work as a waiter for example on their way to the A-List.