In 'walking" marriages, I feel the benefits far outweigh the disadvantages. It does provide for privacy.
Even in everyday environment we interact with people of different hues at work or at social gatherings, which we take in our stride out of sheer compulsion or necessity.
In communities like Mosuo they have evolved a culture that gives due space to every kind of relationship.
And if you look at the system holistically there is a lot to favour it than against it.