The computers are cold, uncaring, unbiased calculations. There is no "correct" calculation--they are all estimates. That means you WILL get different rankings for different algorithms, and that's why we average them. There is no problem here, even if rankings return results that contradict results on the field. There would be a problem if computers consistently return results that contradict actual game results.
So, instead of whining about point differential (which, IMO, is better to leave out), why not campaign for computer polls to be added/removed according to their accuracy? At the end of each year, their overall results can be compared to all the actual game results, and if any computer system shows that it is consistently inferior to other systems, it gets replaced.