If you do a little digging into the reasons this dogma was "infallibly" declared by Rome and why it took so long, you will find out that it was because of the petitions of many RCs who placed their faith in apparitions and testimonies of some "Saints" who claimed that Mary told them it was so (i.e.; "I am the Immaculate Conception" of Our Lady of Lourdes and St. Bernadette). Nothing from God's word nor from the ancient witness of the Christian church ever mentioned it or thought it such a critical component to the Incarnation doctrine.
It gets pretty monotonous having these same arguments over and over again. I sincerely believe the main, maybe the ONLY, reason FRoman Catholics continue to defend it is because their church declares it is something that must be believed. To acknowledge that others have valid reasons to reject it is a tacit admission that they cannot make.
Satan doesn’t like it when we pay attention tot he details obfuscated by Rome.
Another pithy, informative note. Thanks, BB!