The idea that there is a level of acceptable fighting is just another one of those unacceptable behaviours that society has learned to tolerate as some cockeyed societal norm. It's this kind of idea that kept men and women trapped in abusive relationships for decades, and to this day still keeps people stuck in unhappy and miserable unions.
I don't think a relationship that never sees a argument is a good one. It shows that one, or both, sides doesn't stand up for him/herself, or never got close enough where they have to sometimes clash to adjust to each other.
Too much fighting is not a good thing either, but some argument here and there which leads to a resolution 90% of the time, shows the growth of both partners, and that's one of the most important things. A couple that grows together forms a strong relationship. If the couple grows apart, and couldn't reconcile themselves, then they know they're not right for each other.
A relationship without any arguing at all is not a real one.