Absolutely disallow. Consuming or returning floats should be a hard error, absolutely not allowed as it will eventually break.
Such services should be disallowed. Anyone who uses a float to transfer monetary values is not just recklessness, but also malicious. Storing a number as a string allows lossless conversion and that is fine, same with fixed point, integers, ratio’s, etc, but storing it as a float should always be absolutely disallowed.
