I think you should read the tyranny of F/OSS -- There are some interesting opinions in there -- having no structure does not always work out like you would think, secret social structures still get created.
Even worker coops have a CEO and management its just that all the employes are the share holders which is a bit more manageable at scale.
And the scale they're doing it on is also alarming, but I'm relatively new to the startup scene, so maybe I'm wrong
ALSO - They should look at the problems that Valve has had in the past with a "flat" structure
Of course the social structure will evolve, however we're not afraid of 'secret social structures' as the company is fully transparent and we all have similar mindset.
For 3 years we've been all working remotely from our homes - I can imagine, that during this time, any 'secret structures' would have already appeared.