I can see a future where a BNPL loan is not offered if the signals the checkout page collects indicates wealth, since they don’t have an issue of cash flow stopping a purchase. Imagine a loan that has a credit score maximum, not a minimum.
It's no different to the practice of using a credit card for everything and then paying off in full a month later because the credit card interest is lower (often zero if you pay off within a month) than the mortgage interest.
I suspect this is where some buyers will get into trouble. Theyll think they made a payment, or they miss a notification that tells them to send this month's payment to servicer X not Y, and before they realize, boom they are in default and owe all the interest.
For a 3 month BNPL loan to be worth it, HYSA rates must be over 6%, and actually a bit more due to the time value of money; you get CC reward cash after the statement period but it takes 90 days (and up to ~120 days) to get three monthly interest payments.
People with good credit may use them, but it makes zero sense to do so. You always come out ahead by using a credit card and paying it off immediately unless the high yield savings rate is 6% or higher assuming a BNPL loan term of 3 months. Beyond that, it does make sense to use them, like Apple’s 12 month no interest on Apple products with the Apple Card.
Lots of people with good credit are not maximizing credit card rewards and sign-up bonuses, either. Humans are not homo economicus. (And just as a factual matter, there are sometimes longer BNPL terms than 3 months, which changes the math on what is "optimal.")