Re: aikido w/o any of the trappings
Every single group I've started (all two of them) the primary motivation has been so that I can up the training time in the style of Aikido I enjoy doing. It sure wasn't because of any intrinsic need to teach. At my level and that of the guy in the park - we shouldn't even think about setting ourselves up as sensei unless there are extenuating circumstance.
They normally call me Peter in the dojo and the social interaction is a big thing. After practice lunch, trips to the O'furo, dinner parties and beer drinking. I've practiced Aikido in the main dojo, my gym at work and among the trees and rocks.
There is no abuse and the students are getting a good technical understanding of Aikido. It's a given that just about everyone in the group will be moving on - what more can we do.
I find the friends in the park scenario completely admirable. So what if the group breaks up - perhaps one or more of the students will have learned enough good Aikido that they can choose wisely when they look for a more permanent group.