Craigslist explicitly tells people selling on it to avoid accepting online payments (like, PayPal) and only work with cash because the online payments are reversible and sellers constantly get scammed. You have to remember that transactions involve two parties, and it isn't somehow always the case that only the ones on one side matter.

The power balance simply isn't always "seller who is selling a large quantity of easily-replaceable items that might be a dud can easily amortize the cost of fraud across all of their payments by high margins"... sometimes it really is "seller who is selling a small quantity of expensive or precious items tends to get scammed by anonymous buyers who abuse chargebacks ".

Venmo[1] does not have reversibility. Cash does not have reversibility.

If users really wanted credit card functionality at the expense of its costs, you could build that as a layer on top, without forcing everybody in the system to use it.

And consider, most disputes is not just about the quality of a product. That is handled with regular refunds. Credit card disputes are a lot of times because of fraud or card skimming, which is very often because the system is not very secure to begin with. Secure cryptography can remove a lot of this type of fraud.

[1] https://help.venmo.com/hc/en-us/articles/235171088-Cancel-Pa....