As others have said, it is a good feature to have. If anything I would rather see a scaling penalty for those that ditch early, but before something like that is done need a way to deal with people who afk/logout during instances. Ideally the penalty for leaving before a mob is touched would be the same as the longest queue time someone in the group had.

Also the OP makes me glad I still think of Newb/Newbies and NOOB separately. To me typically NOOBs don't learn or refuse to listen to anyone, where as the Newbies do learn and at least listen to others, granted some can be slow learners.