The latter. The problem isn't the members being taught, it's the members teaching. There hasn't been a well led and well organized attempt since W26.
Are you sure? On UK I've led a couple of rim tribes and as much as I've tried to filter applicants and filled the forums with digests, I've never seen more than one or two members even comment on them, let alone act on them.
Most people just don't see the competitive side of TW, or dismiss it as irrelevant (Well, they tend to put it a lot less eloquently...). A person has to want to learn, if a teaching tribe is reaching the right audience, even an average player such as myself can pass on a lot of knowledge. I don't think a teaching tribe should be about getting people to the top ranks, but rather giving them a decent understanding as a foundation, then letting them learn from their own mistakes. Give a man a fish and you'll feed him for a day, etc.