Whatever Happened to Knitting Machines?

I remember coming up and my mom had two of these things. When I was home alone, I would play Prince albums and pretend like her machine was a synthesizer for Purple Rain remixes.

Whatever happened to these? Do people not use them anymore? I never see them in stores and it doesn’t look like anyone has improved on the design (certainly not the grinding/shushing noise it makes when in motion). Are they not as useful as they are advertised to be? Now that I’m thinking about it, I don’t even remember my mom really using hers but once or twice.

Anyone have one and still use it? When did these stop being a “thing”?