I am not in awe of the teaching societies - far from it, but I also have a healthy skepticism about anyone who is self-appointed.
development has been based on that informality.
Whoever thinks they have enough knowledge can teach,
or in many cases other people, potential students,
cajole someone into teaching or coaching them.
I very much doubt that any one organisation could succeed in being either 'over-arching' or 'restrictive', but the alternative of everyone going their own way seems to me to be a very inefficient way to either learn or grow the dance.
development was/is very inefficient, that's life. Talking about efficiency
starts alarming thoughts of bureaucracy and autocracy. I think not!
Tango was evolved informally over many years and its worldwide spread
is causing another evolution, part good and part not so good. But thankfully
Tango is alive and not pickled into books of steps and tiers of diplomas.