I'd go so far as to say 3DoF was a massive setback for popular perceptions of VR.
Low-resolution spherical imagery and video is just not that impressive, and that's all you get with 3DoF. Contrast with the presence and immersion you get with even the cheapest 6DoF headsets, and it's not even the same technology category.
So, now we have a bunch of people walking around thinking they "tried VR" because they had a Gear or a Go or a Cardboard, but they didn't get what the big deal was about.