Do you have any evidence for that at all? The majority of fintechs I can think of (at least the ones that provide cards, either debit or credit) do so on the Visa or MC payment rails.
One of our greatest failings as a society is our abject failure to teach people finances. It's as critical to our lives as breathing, eating, and crapping, yet the vast majority of people can't even count change let alone understand credit.
Incidentally, anyone telling you BNPL is good for you is trying to milk you. Please just don't and stick to cash/debit or good old credit cards, for your friends' and family's sake if not yourself.
The downside for the customer is that it promotes overspending, which could be argued as a net negative on the whole. A careful consumer could make use of the free loan, investing the cash elsewhere during the loan period.
[1] https://www.bitsaboutmoney.com/archive/buy-now-pay-later/
The operative quote in support of this from the link, in support of subsidizing those who don’t and almost more damning because even cash users are subsidizing it as the overall price gets raised to roll in the cost of all the people who do use CCs: “Credit card issuers explicitly and directly charge the rest of the economy for the work involved in recruiting the most desirable customers.”
This is not much different from Microsoft fighting open source, Apple fighting right to repair, or Google fighting the CCPA.
As always: Cui Bono? Follow the money.
Keep in mind that payments are broader than cards.
I imagine you live in the US.
But if you look at some of the top fintechs in both the US and Europe (e.g. Chime, Revolut, Brex, Robinhood, SoFi, etc.) all help extend Visa and MC's reach.
I'd suggest you read around the threads here to see all the comments about the EU and Japan.
Maybe it is because I am in Germany, but merchants here only accept cash, girocard and credit cards - online shops obviously have a wider selection that regularly includes Paypal in Klarna, but I wouldn't expect credit cards to loose a lot of market share to them.
So in which geographic regions is this actually the case? Do you have any source I could read on this as I am quite interested.
UPI, Pix, FedNow and many others make direct payment much easier. In Brazil is now more common to accept Pix and not accept credit card than the opposite, although almost everywhere accepts card. But literally everywhere accepts Pix (and every app that uses it).
I just want to clarify, because this phrase looks like a huge understatement.
Beggars on the street accept Pix.