The right tool

When communicating in real life, 'showing' is so much better than just 'telling', but, participating in developing a concept or idea is far far better than having one presented to you.
An idea communicates so much better when you see it develop in front of your eyes, rather than having one presented as a packaged done deal. That's what happens on a whiteboard isn't it? You pick up a marker and start writing, others can see what you are doing see the idea develop & they contribute or prompt or question or ... The whole thing takes on a life of its own. Great fun as long as the whiteboard is big enough and there are enough markers to go around.
Documents and presentations don't come close.
We modeled skrbl's unrestricted, freeform, click anywhere and type interface to be as close to a whiteboard as possible. Whiteboards are great in the office, in the classroom & in boring meetings (where they can offer respite from mind numbing banality). It didn't make sense that there were no whiteboards on the Net.
Efficiency requires the right tool (or the closest proximation) for the job. The flexible interface took some doing, but I think it was worth it.