The answer is simply "no one". There is responsibility to be had on all sides!
The second common industry mistake made by talent according to our long term actress friend, Colleen, brings up some good questions! Have you handed over the authority to move your career forward to the hands of fate?
No, you don't have your own TV network or movie studio. (Arguably, that's a good thing these days.) You cannot just create yourself a lead role or series regular gig with a wave of your hand, and no matter how much better you think life used to be (e.g. under the studio system or some other mythical golden age), you never could.
There is certainly some luck involved in having a long and successful career in the arts. But if you look at most of the people who made it, there's a lot of hustle involved. They didn't have some agent ride in on a winged unicorn, nor did they land ONE magical role that made them. It took work to get the right pieces in place. Or they landed several roles after a lot of busting hump.
Control what you can. Pick a month—any month—and get cracking on something. And never stop. Ever.
As a talent, there are things you cannot control, but focusing on those things will keep you right where you are now. Move forward -- and grasp the things that you can control. What are those things? Well, this blog has already answered that question many times over. Check out these posts for more ideas and then think outside of the box and create your own.
Innovation and creativity are the things that draw you to being a talent, so tap into them for the longevity and sake of your career!