this doctrine, by itself, doesn’t impact one’s standing before God with respect to their salvation
This doctrine is not a stand alone, but it is an integral piece in the mosaic of faith and salvation begun by Jesus and continuously confirmed and proclaimed by the Church, at Christ’s command. And again, it is not meant to defend Mary but her Son. And conversely, when one attacks this doctrine, one attacks not just the Church and not just Mary, but her Son. The Church ALWAYS focuses its exegesis and theology on the person of Jesus.
The Apostles did not accept Jesus as Messiah based on one thing He did or said. In fact, it was one particular thing He said that caused many to reject Him and leave Him.
Peter says in the Gospel of John, “To whom shall we go? You have the words of eternal life. You are the Christ. We have come to believe that you are the Holy One of God.”
You correctly stated that “this doctrine, by itself, doesn’t impact one’s standing before God with respect to their salvation”, but then you also said this doctrine is an integral part of salvation.....
I take issue with that, because as you noted this issue doesn’t impact salvation one way or the other. Therefore, it’s contradictory to say on the one hand it doesn’t impact salvation and on the other that it’s an integral part of salvation.
You're implying that people believing that Mary remained a virgin forever somehow helps them come to trust in Jesus and thus obtain salvation. Conversely, that means you believe that people won't come to a true belief in Christ unless they first believe that Mary remained a virgin.
That's ridiculous. All that is required is a child-like faith in Jesus. One doesn't even have to worry whether Mary remained a virgin in order to be fully devoted to Jesus.