We do need external teachers for a while to guide, teach and hone our understanding and skills. But, at some point, all a teacher can do is lead us inward. Like a big cosmic U-turn, the guru is ultimately only trying to lead us home.
At some point, every student must leave their teacher. It's a built-in principle of yoga. Parents raise children to be able to survive on their own at some point; its the same concept between teachers and students of yoga.
The controversy surrounding a recent yoga video serves as a gentle reminder that we are quick to judge when we have no idea where someone else is coming from. People often overcome mountains of adversary to be in a place where they can shine.