This is one of those "if you don't already know" topics.
The feds cracked down on it earlier this year leading up to the election, but it's back.
Why can't anyone say what it is?
I can, but I won't. The state doesn't like it, because it bypasses the points at which they control the system (largely without due process) and I don't wish to make their jobs any easier for them.
Because it’s just a provocative fiction in their minds.
In most countries I think you'd need to know someone with crypto who could use the cash and do a swap. The website localbitcoins that used to sort that is closed. Cambodia has cash to crypto dealers on the street if you are over that way.