Completely eliminating any risk of chargebacks mostly shifts risk back onto the customer; I don't think it's a net benefit. Some businesses seem to intrinsically have sky-high chargeback rates but I'd prefer that those businesses simply not exist rather than put up with the existence of crypto.

I once bought donuts from a food truck with BTC and the donuts were good but the payment process was really slow.

I own a small online business selling custom-configured RPIs and chargebacks are terrible. Businesses build reputations but expect their customers to be anonymous every time. It would be far better if chargebacks were eliminated and customers could review the merchants to reduce fraud. Putting all the risk on the merchants is backwards.

The merchant is the one who has more capital and more information about the product he's selling. I think it's fair that the merchant bears most of the risk.

Credit Card/Chargebacks are not a silver bullet. Countries like India have alternative payment methods without chargebacks and some Merchants insist on them.

And 8 years later the fees no longer make it viable for even that niche use case.

What fee? Are you talking about a specific currency or all currencies? In Celo currently fees are 0.1 cent per transaction, for example.

I've never heard of a single physical item being sold for any other cryptocurrency, only Bitcoin.

How would a merchant of physical goods even know about something like Celo, whatever that is?

Adoption takes time.

Surely you recognize that this is a bad faith argument? The average transaction fee today is around $8 USD. That's a small price to pay for knowing that a transaction is set in stone.

It's a pretty high price to pay for donuts though. Especially since it's kind of hard to reverse a donut transaction after you've eaten them.