The parent comment is making a philosophical/ethical point - there is a lot of power concentrated into two private companies (Mastercard and Visa). They are the gatekeepers to being able to take payments, without them you can't have consumer income, and they make moral judgements that make it hard to operate certain kinds of (legal) businesses.
Sure, but why not use a stablecoin cryptocurrency?
Why do we need to invent an all-new alternative currency and asset class just to use these technologies? Why do I have to invest in 1 of 1000s of altcoins just to arbitrary change numbers in a shared ledger?
Because the US monetary policy and inflation, and USD not being backed by anything, and because people don't want this power in corruptable governments.
This is not even some dispited facts (that this is one of major reasons for why some people want a new currency), this thing has been discussed over and over into oblivion, since the beginning of cryptocurrencies. It is a question that has been answered millions of times at this point. You just haven't researched any of it.
