Great graphic. I found this easier to grasp in the visual (layed out) format than in Anil Mammen's original post.
Coupla points:
"Imparting knowledge" doesn't have to be a "top-down" or unidirectional activity. Socrates showed how to impart knowledge by asking questions.

The definition of "Learners as Teachers" as "the blind leading the blind" is spot on and very funny. However, "learners as teachers" doesn't have to mean "the victory of amateurism over expertise". It only means that if one assumes that "learners as teachers" means expecting learners to be or become experts in something they are not, merely to make them (or the teacher) feel good. There is also the possibility that, trying to teach someone else can be a key catalytic factor in helping structure knowledge in the learner. In other words, "learners as teachers" refers to a learning process, not a learning product (why would anyone go to the inexpert rather than the expert?).

It's easy to fall into the ideological trap and start believing that "teacher-centric, bad; learner-centric, good". But rather than judge the idea on its merits, I prefer to look at results: a top-down, teacher-centric, lecture-style approach can be a very efficient, as well as stimulating, method of imparting knowledge and sparking ideas (when done well, but that applies to anything, does it not?). What determines if it is or not depends a great deal on the kinds of audience. A lecture-style approach may be efficient, a learner-centric "project-based" approach may sound fun and be politically correct, but if neither of them engage the learners and generate energy, what's the point?