I guess the fact that I was heavily involved in open source (where every single project used .org domain if available) never made me think they were in any more "reputable" than eg. .com.
So, how did anyone ever get the notion that they were restricted to non-profits? I know that "choosing your domain name" guides at the time mentioned how .org is a good candidate for non-profits, but how did that evolve into "only registered non-profits can get a .org domain"?
I believe RFC 920 [1] was the guiding document when .org was established in 1985. It cites no restrictions on .org second level registrations, merely that "ORG = Organization, any other domains meeting the second level requirements."
If you look at the provided examples of .org miseducation, they seem to be quite old.