Okay, let me try this way:
Monero is perfectly distinguishable from any other forms of money therefore if some social convention somewhere prescribes they will not accept it then it is non-fungible.
"Fungibility refers only to the equivalence of each unit of a commodity with other units of the same commodity. Fungibility does not relate to the exchange of one commodity for another different commodity"
https://en.wikipedia.org/wiki/FungibilityAlso, from the same source:
"A good is fungible if one unit of the good is substantially equivalent to another unit of the same good of the same quality at the same time and place."
Notice the wiggle word in there. Fungibility is subjective.
Maybe this bit is also relevant to our discussion, waddayathink?
Fungibility does not imply liquidity, and vice versa. Diamonds can be readily bought and sold (the trade is liquid) but individual diamonds, being unique, are not interchangeable (diamonds are not fungible). Indian rupee bank notes are mutually interchangeable in London (they are fungible there because law) but they are not easily traded there (they cannot be spent in London).
"Bitcoins are mutually interchangeable in Fiatlandia (they are fungible there) but they are not easily traded there (they cannot be spent in Fiatlandia
because law)."
I think a quick look at what is actually non-fungible shows how mindless our debate is...