If you read the article, the director asked that the show be handheld, so no regular dolly on track.
Sure, dollies moving on track are done all the time... why would one photo from one production make you think that dollies on tracks are no longer being used in the industry? If you see a shot of someone handholding a camera, you wouldn't think that all movies are handheld today?
I don't know the name of that particular dolly, it sort of falls under the general term "rickshaw rig" in some places, something that a steadicam or handheld operator can ride on. Many of them are built one-off by someone rather than mass-produced but perhaps that one exists in a catalog somewhere.