Viking River Cruises is just a couple of years old, and it is growing at an amazing pace. While I'm confident that it is Vikings intention to train the rez agents so that there are few--if any--errors, when a company grows this quickly, it is hard for Human Resources to keep up with the need for additional fully trained agents.
I'm not certain where you got the information regarding Virtuoso. It happens that Virtuoso is one of Viking's biggest producers, with millions and millions of dollars in bookings every year.
I hope you are pleasantly surprised when you sail on Viking. All's well that ends well!