I may well agree for small self-contained (insular?) groups but any larger; in other words; more than two member/site groups I think a structure naturally occurs with a hierarchy, leadership and a common set of rules, however informal.
IMHO one of the reasons Aikido has spread globally is because there is a formal structure in place. This applies to the Aikikai, Yoshinkan and Tomiki styles equally as well as "newer" groups such as Iwama and Ki Aikido.
My point was that there are many different forms of organization - many of which work better and more successfully on a large scale.
Professional organizations and educational accrediting organizations are two that come to mind - and do quite well without duplicating the system of mail order ranks that the Aikikai has ended up with.