The trouble with this idea, it seems to me, is that the Primitivists want to pick and choose what technologies we have and how we use them. But that's just not possible. Technology is an interdependent whole, you can't have bits of it without having all of it.
Want books? Basic medicine? A bit of electricity? Okay, that's a chemical industry, refined metals production and a mining industry right there. Then people are going to want to improve them. Better machines to mine with, better ways to refine the metals, medicine that is a bit more sophisticated. They'll have the desire, and they'll have the tools to produce those advances, so what will stop them really? Primitivists talk as if all these things are central decisions, that "we" can decide that we will invent electricity, but not move on and have electronics, or that we will have simple electronics but decide as a society not to develop computers.
But these things are historically done by individuals or groups. If you have "a bit" of electricity, how do you propose to stop people from using it for lighting, heating, cooking? And when they do, what's to stop them from inventing the telegraph, and then simple electronics, and then the transistor, and so on. Is there going to be a dictatorial government to enforce these edicts?
Or is it just part of the fantasy that everybody in the whole world will agree to all the rules and limits, rather like the idea that 80%+ of the population will just quietly vanish someday?