You can finish an AR-15 80% lower with commonly available hand tools in a few minutes. I don't see how the CNC machine that automates this procedure is somehow "dangerous". It's just a smaller, cheaper, and more specialized variant of a regular CNC machine which anyone could already buy.
You're 100% correct-- I believe it's more legally dangerous to those purchasing it than physically dangerous. It just lowers the barrier of entry and creates a frictionless path where someone buys a bunch of products, combines them in the way they were intended and they commit a felony and get a reliable firearm. When combined with the rhetoric that doing so is patriotic or in support of your rights it becomes worrying.
It sounds more frictioned if anything. Both would be pretty simple detective work. "Shooter had gun and ammo. Shooter bought from Bob's Guns. Case closed." vs "Shooter purchased receiver, ghost gunner, guncotton, loading bench, cases and primers, and prefabricated bullets/lead and casts. Case closed."
[0]: https://www.youtube.com/watch?v=ccO1Day60sA