It’s all really quite simple. People just want to find loop holes or use wait for it…“logic and reason” to go around Church teaching.
I’m glad someone finally brought this up. It is my opinion that NFP exists in the first place because of “loopholes.”
If you read about and research the Church’s position on various matters, you’ll see that they do it in a very methodical and legalistic manner. The Church’s position is extremely carefully worded. It also must be, especially on matters of faith and morals, because they claim authority and/or infallibility on such matters.
I’ll give some examples of careful wording. There is plenty of Biblical support, especially from Christ and His Disciples, on marriage. Matters pertaining to marriage are discussed in great detail. You’ll note that the Church’s position is that sacramental marriage can’t be dissolved…
by man. It never states that God can’t dissolve a marriage…that, my friends, quite frankly, is very good legalistic type research and writing.
Same with mortal sin. Most people believe that death in a state of mortal sin equals eternal damnation. However, the section on suicide clearly leaves final judgement in the hands of God. The section on martyrdom also leaves that possibility open, though the wording and reasoning are more vague.
OTOH, this is far less true of matters pertaining to sex in marriage. Yes, it is blatantly obvious to all in the Bible, Tradition, and common sense what the true purpose is about, i.e., raising children. But when it comes to the issue of handling family jewels, the support is extremely weak and very open to various interpretations. The word redefining/twisting/spinning is truly stunning, and likely the reason why even those that support it eventually have to throw down the Magesterium/Infallibility gauntlet because reason does not suffice. Loopholes is the way NFP has become to exist…easy to do because the support is vague…that is as clear as the day is long.