I guess what I mean to say is that someone endeavoring to write a cycle-accurate emulator wants every game to work exactly like it did originally regardless of what bizarre hardware-specific hacks it relies on. For someone who just wants to play any of the top 20 most popular games on a system and isn't too concerned with minor deviations pretty much any emulator is going to suit their needs (in fact it's a common model to have hacks in the emulator just to make a particular popular game work right).
