Fungibility means that one thing can be differentiated from another. In a basic sense, drops of water are fungible. Dollars are non-fungible, because 1 dollar is not equal to another cash dollar. That other cash dollar could be from a set of marked bills stolen during a drug buy, or it could be a rare serial number making it more valuable. It's a binary state of "is this thing completely indistinguishable from another of thing of its kind"
fwiw, the person you're responding to doesn't seem to be using the word in this manner.
I am using it in that manner. Ethereum OFAC compliance is enforced at the protocol level [1] so not all Ethereum are equal. Just like your "drug buy" example, some Ethereum are tainted. In fact, thanks to the public blockchain, I would argue crypto is far more "non-fungible" than marked cash.
In general, cash is fungible. You gave an example of a "shade of fungibility" with marked cash used in crimes. Unfortunately, reality is not binary. Ethereum is fungible to the (increasingly small) non-OFAC compliant nodes, but non-fungible to the OFAC compliant nodes.
I don't understand how Tornado Cash (DPRK tool to evade sanctions) + Office of Foreign Assets control made Etherum non-fungible either, sounds like rambling to me
