I love what Peter Grey has to say and I'm happy to see him published by a mainstream publication like Psychology Today. I saw him speak last year at an unschooling conference, and he'll be back again this year, as well. Anyone interested in unschooling and raising children would likely appreciate his work.
http://www.psychologytoday.com/blog/freedom-learn
I would say that what is called "formal play" is not really play at all. Isn't it part of the definition of "play" that it be informal? By formal, I mean "managed or directed from the outside" and informal, I mean "self-directed," which (as you say) is another way of saying "statism" versus "anarchy."
Cheryl
There is self-knowledge after children.