the silly thing is, the fools that think fungibility is a needed thing to become 'money' so much so they are wiling to break bitcoins open transparency, audit policy just to get their real agenda of their selfish whims of telling people bitcoin is not fit for purpose and everyone else should 'off board' or fork off to altnets

fiat is not fungible
getting fiat from a relative on random occasion in small amount= gift= no tax
getting fiat from a relative after death in large amount= inheritance= inheritance tax
getting fiat from a employer = income tax
getting fiat from customer for a product = sales tax
getting fiat from an investment = capital gains tax
keeping alot of fiat after bills = wealth tax
keeping fiat in a family/corporate trust = capital gains tax
use fiat to buy property/shares = stamp duty
businesses that keep fiat after costs = corporation tax
have a low income or a basic personal account = low ATM withdrawal amount
have a high income or a business account = service charges and subscription fees
using debit/credit card fiat = 'service charges' (sometimes customer pays sometimes merchant pays)
(the list goes on)

yep every day peoples 'money' is treated differently depending on who handled it and how it was passed.

fiat has just been around so long that people dont think about all the differences each allotment is treated depended on how it was received. going to be spent
so in short fiat is not fungible. people just dont think about its treatment

and yes banks do question utility of peoples spending or receipt of fiat
and yes if you tried to buy a house with a suitcase of cash. they will question it
as would trying to pay a court fine in pennies or bank notes with odours of drugs

so dont pretend fiat is fungible to then pretend 'fungibility' is then the good excuse to want to break bitcoins 'taint' (tracking back to its source creation) by bastardising bitcoin by pretending 'taint' is about criminal checks/anti-privacy that need to then remove taint.

the taint actually solves an incredibly needed accounting policy of money. which is about trusting that all coins can be tracked back to its source creation coin reward so that no new coin can be introduced outside of the mining/coin creation process.

it seems its the same group of people meriting the topic creator, are the same group that want to tell billions of unbanked people that bitcoin is not fit for their daily normal use, and to fear/avoiding just using bitcoin as-is, whilst then advertising some other silly lock/service/altnet that takes peoples individual control away by having to rely on some service/lock/altnet to allow them to spend value after wasting more time to set up this silly advertised service/altnet membership

coinjoins are not needed. they make the experience of bitcoin delayed/slower due to the time it takes to 'mix' and ends up giving said users a bad 'suspicion rating' just for using it.(defeating the 'privacy' / anti-kyc stuff it pretends to solve when then depositing into exchanges)

if people want privacy i have no issue with those people using such service/locks/altnets. just dont try pandering your silly schemes onto regular people that dont want to have to have more headaches just so suspicious people can get the clean coin at regular peoples loss

so you privacy guys, you lot should go play with altnets and convert your coin to msat/lbtc in some confidential network and mix your crap over there.
instead of wanting to break bitcoin audit rules and spam the network with mix tx spam while telling everyone else to avoid using bitcoin