[quickthrower2]

Fraud. What if you are required to return the inward deposit but cannot obtain the corresponding outward transaction. Or you can but lose money on the rate.

Bank transfers being reversible is the reason for the difficulty buying crypto at least years ago, maybe it is easier now.

FX services in my experience have a lot of staff and ask a lot of questions even for established accounts. Also the banks ask a lot of questions (although that is to the benefit of the FX service reducing the likelihood of fraud hitting the FX)