To be honest I would agree if any merchant is accept bitcoin in their payment system, they the "merchant" could directly exchange their crypto when the money is arrived so they didn't really care much about the price of bitcoin volatile and unstable price.

But the real benefit is from the customer, lot of crypto user gonna see this as a positive movement So they didnt need to exchange their money move to the bank first and go buy a thing. They can directly buy just do with a couple of click.