Since the Dolphin team puts playability above accuracy, the emulator can keep moving the goalposts towards perfect emulation, while still remembering that an unplayable emulator does nothing to preserve the source material.

Compare this to the MAME situation, where most early 3d arcade games are completely unplayable, and will remain like this for the foreseeable future, because the way computers are going, there is no way in hell we'll be able to emulate those old, custom graphics cards with full accuracy and full speed using only general purpose CPUs.