THEY don't want IPv6 implemented, because IPv6 easily ensures that everyone and their evil twin can have a fully-accessible IP address, allowing them to directly communicate with each other without paying extra rent to the ISP for a "server" or "special" (routable) IPv4 address.
If users' systems can directly communicate with each other, there's far less need for centralized sites for everything where it can be controlled (for example, YouTube for video). Deep packet inspection is an option to spy on people looking for copyright trespassers or subversives, but with encryption becoming more readily available, that gets harder, too.
When anybody who wants to can set up (or even buy "canned") a media appliance running something like "MediaGoblin" to share audio, video, text, photos, etc., or VoIP servers like Mumble or various WebRTC-based systems for conferences and "phone calls" and other audio, servers for federated instant-messaging systems or "social media" platforms, etc. etc., and just assign those systems one of the overflowing bucket of publically-routable IPv6 addresses that everyone can have, it'll remove a huge amount of control that big media and telecommunications corporations (and governments) currently have. They don't want that.
Don't try to tell me it's not true, I can hear 'em talking about it on the radios the CIA implanted in my teeth.
But, seriously, my lazy, cheap, asshat phone company can't/won't give me more than one publically-accessible static IP address, probably really because of the ancient crappy DSL modem/router they force us to use and not being willing to have their executives skip lunch for one or two days to pay for the infrastructure upgrades.
Note that this doesn't necessarily mean it's not a secret conspiracy on a global scale overall, though...