This type of group blogging is very popular. Tutor always has special position in relation to students, has all the control and in some cases, doesn't have to post at all! Many are desperate to get some traffic and will easily guest blog for free. It is much better when guest blogger gets paid to post. Some blog networks that work this way are very successful and it seems like their number will only increase.
I don't say Tutors and Students type of group blogging is wrong. It is not a hoax or the way to take advantage of greenhorn bloggers. I think it is extremely hard to build your blogging empire and sometimes even impossible. However, real world examples are there to remind me I'm wrong. There is army of bloggers out there struggling to get 1000 visitors per month even when they post every day. As guest bloggers they can get more visitors to their blog in a single day. In the end, both tutors and students are satisfied.