I think anyone would agree that there are claims not explicit in the text of scripture but that can (and should) be extrapolated. For example, in the four testimonies Christ doesn't say explicitly the exact words "I am God"--and atheists think that's a trump. But we know that we can extrapolate from "before Abraham was, I AM" and other statements He gives, and we know that God had previously said He would come and gather His sheep scattered, that He would be the good shepherd--and many more points in scripture that clearly support and necessitate that Christ is God. We can extrapolate clearly to the conclusion. And then more conclusions from there, sure.

So it isn't automatically false when someone states something not explicitly stated in scripture, we see--but there must be the basis in scripture *and* it must not contradict other passages of scripture (unless one also claims the specific passage contradicting is a later addition that doesn't belong or was corrupted, whether purposefully or by accident).

No where does scripture explicitly say that Mary was sinless, and no where in scripture is there a passage that implicitly necessitates that she was sinless. It does however say in scripture that none were righteous, that all were fallen, and it does say that the Israelites--and Mary was an Israelite--were condemned to death by the law, as the Bride had been adulterous. These--which are in scripture--would contradict Mary being sinless.

The reason Mary not being sinless matters (in the context of this conversation, not as a whole) is that the claims the RCC makes about her (that she did not die an earthly death and/or that she chose to set aside her life) are only necessary *if* she were sinless.
And we know from scripture that it *cannot be* that she was sinless, as she was 1) of Adam, 2) an Israelite--meaning of the Bride condemned by the law, as told by God through the prophets as we have received through scripture, regardless of a recieved (man-handled) tradition offering a contradiction that's not scripturally based and is an unnecessary exception.

The reason this matters is that this inflation of Mary's nature is the basis for the inflated emphasis of Mary's role or ability in intercession.

I would point out that the beat of "The Father, the Son, and the... " begs for "Mother", and the RCC puts Mary in that role--not going so far as to make her God-- but "Mother of us all," "sinless," "Queen in Heaven," "closest to God for intercession."

A typology of Eve seems diluted and inflated, consumed, lost in the sauce, by a member-of-the-Godhead typology given to Mary by the language and claims of Mary's nature the RCC uses ("sinless," "Mother of us," "Queen in Heaven," "closest to God for intercession," etc.). Granted, of course, not quite a Mother that's part of the Godhead, but approaching closer to that than to only the nature, role, and importance explicitly given in scripture or that which can be extrapolated with a scriptural basis.

(just a good animal for your time)