Maybe you could find these posts you claim exist. Are you sure you didn't just read too quickly and reverse the claimed causality, i.e., that both the Immaculate Conception and Perpetual Virginity are appropriate because Christ is divine -- they didn't cause the divinity, but were caused by it.
If it were on another thread, I’d provide a link. Since it’s on this thread, start at the beginning and scroll through. You’ll see them.
One poster in particular claimed that had Mary not remained a virgin after the birth of Jesus, he would have been no better than Heracles.