Youtube already had stereoscopic support, but there were not many clients available, content was limited and difficult to create with 3rd party solutions that all cost money. It never took off and couldn't ride the wave of the studio and CE company driven 3D momentum, which quieted down after a while anyway.
This time Google ticks all the right boxes. Client devices on iOs and Android. The videoplayer everyone uses. A $5 cardboard enabler. A capture platform with GoPro and free assembly software.