Go4it:
It used to be even worse here for teaching, but some improvements have been made. Now it is at least possible to give handicap stones, and there is an alpha-numeric grid for identifying points on the board. (This was not always the case).
The biggest impediment to playing teaching games here is the lack of an "undo" feature. So you can't go back and demonstrate alternative moves without replying the entire game.
As for rankings - I find it amusing that people even care if they gain or lose points. But assuming that there are people who, for some reason, think it is important, there is a solution that is used on other sites. One could have the option of playing an "unranked" game that has no effect on your score. Then those precious and valuable points would not be affected by playing a teaching game.
The third suggestion is to allow more than 8 people to watch, so that when a stronger player is teaching, the maximum amount of members could observe and benefit.
