@AlainAlam,
I think you need to rephrase "they played a direct role in breaking marriages up" . The reason why the question of lewd practices within the framework of a marriage even came up was because one of the marriage mates abhorred such practices, this is why the original article mentions "the offended party". There was a sister in my old congregation whose husband wanted her to perform oral sex on him. She was disgusted with this and found him disgusting. She was torn between "obeying" her husband and her belief that what he wanted was a "lewd" practice. This was in the late 80's so no divorce for her! However, she would have loved it if she could have divorced him on the grounds of porneia.
What I find disturbing though is by whose authority can the WT say it's ok if you got an unscriptural divorce? I guess they must reckon that since whoever did this, did so in good faith, i.e. believed what the WT said about lewdness within marriage being porneia and therefore Jehovah will not hold them accountable. But the question remains, will Jehovah hold those who made such assertions accountable? Well you already mentioned that this mistake was not intentional, therefore perhaps Jehovah did overlook it...
In summary, I do not think this was a case of breaking marriages apart. The marriages were already broken if there existed sexual disharmony among the marriage mates. And as regards unscriptural remarriage, well that was no fault of the marriage mates who were only acting on the WT's misinterpretation, and this misinterpretation was a mistake and not done out of malice.