St. Ephrem the Syrian was definitely in the minority among the Eastern fathers. When you use the words logical conclusion---that's the heart of Scholasticism----trying to insert too much logic into the mystical. Aristotleianism v. Platonism. To the Eastern Church it was sufficient that Mary was sinless in her personal life-- Mary's being or not being immaculately conceived did not add or detract from Christ's divinity.
That's the heart of the difference between East and West. God did indeed give us reason, and many Eastern Christians are wary of using it in theological endeavours. What is the reason for this?