Strict adherence also creates a problem with MAME not accurately representing the game as it was on the actual hardware. On the real machine, the game played smooth. People experiencing this game through MAME years down the road with no access to the original hardware will think that's how the game behaved on real hardware.
Over the years I've learned that hacking drivers to make a game run better on modern PC hardware has it's own share of problems and doesn't jive with MAME's goals. I'm merely suggesting that the current stance is less than optimal and can lead to misrepresentation of how a game was displayed. Perhaps if refreshspeed was a bit more intelligent about how it alters a games speed?