Even when teachers move to a more student-centered approach, they still exercise control, and the class depends on them to a greater degree for coherence. The teacher holds everything together. A couple of obvious ways are that much of the communication is in writing rather than in speech and that more people can be active at once. Even during small group work in a traditional classroom, students have to take turns to talk. They seem to have far less fear of embarrassment or retribution than with oral interactions.
Students are at best partial participants in cohesion- building for classroom discourse.
Doing so is frantic hard work, and probably counter-productive in any case. Here, each person is involved in building cohesion, but it is of a different nature, as described more fully later. Class time belongs to her. It is the time for her to perform. In a network-based class, again depending on the software, students exercise far more control.