Sure, Joyent (and others) has "deployed hundreds of thousands of zones into production over the years", but you guys are the only well-known, large-scale, public hosting service using zones (and you're damn good at that, no doubt about it!)
Now compare with dotCloud, Heroku, Dreamhost, 1&1, Mediatemple, OVH, Amen (just to name those I can remember without doing an extensive research): those guys have also "deployed hundreds of thousands of Linux-based VPS into production", using VServer, OpenVZ, and more recently, LXC.
Don't get me wrong: I'm a big fan of Solaris (and its heritage); I have lots of my marbles on ZFS; I hacked basic ZFS support in Docker just for fun a while ago; and if I knew better, I would love to find a way to run sub-zones and a ZFS pool in a Joyent SmartOS instance and port Docker to your platform. But there is a helluva lot of Linux hosters out there.
I'll close with a lovely paraphrase: « Perhaps LXC containers are a new technology for you, but understand that it's not new for everyone; some of us have been doing this for a while â widely deployed and in production. » ☺