Last year, when I argued the gTLD plan was a nefarious money-making scam cooked up by ICANN and large Internet corporations, a central premise of my rant was that Google and the rest of the usual suspects would snatch all of the best gTLDs for their own sites. I suggested that Facebook would probably buy .fb, allowing you to navigate to their site by just typing in something like "w.fb" or maybe just "fb" (I'm not sure if TLDs can resolve directly to a host as second level domains can).
I never once thought that Facebook as the owner of .fb would permit you or I to register a subdomain within .fb. My understanding was that all gTLD buyers were left to their own prerogative, be it exclusive use of the gTLD for their properties or leasing of subdomains in the traditional sense ala .com, .net, et al. In all the press coverage I consumed about the gTLD matter last year, I never assimilated a requirement for leasing of subdomains to the public.
Google's behavior with .dev is just a sideshow to the main attraction of silliness that is gTLDs.