Gammon exist all over the world and throughout history, the ancient Romans were probably all "I don't want to use the more user friendly system. It's not ROMAN ! Reeeeee!" And the mathematicians were rolling their eyes and just pandering to them by rendering the answers in Roman numerals after for a quiet life. Mathematics was all Greek or Arabic so it made sense to use their number systems and notations, but there was probably some real loud mouths who took personal affront to it, despite probably not knowing their way around an abacus.
Same happens today with metric and imperial measurements in the UK and USA. In the UK there were actually people who were so against having metric weights on goods sold (they were allowed to put imperial on as well but only after the metric and not as prominently) that they were willing to take a fine or possibly even serve jail time if they kept at it.