There is some truth to what you state. I also find it interesting that there are some Protestants who swear by notes contained in Bibles as if they were somehow inspired along with the scripture themselves. I suspect the Catholics take their notes more seriously. But none of these notes are inspired.
I have no problem (as I did here) in voicing my opinion that there are errors, not only with Scofield, but with Calvin and Luther. There are certainly errors with some of the early church fathers writings so what would make them special? Why, heck, I would even go so far as to say there's errors in my doctrine, but, hey, that's pushing it. ;O)
What is important is that we identify these errors and own up to them.
In my own defense I'll say that I've never claimed to be personally infallible, and I'll go as far as to say that even in that, I might be wrong.
:-D
But back on the issue, there's no Scriptural witness against Mary's Perpetual Virginity. Arguments regarding "Jesus' brethren" are based upon misunderstood biblical cues that Scofield himself understood correctly. Protestant argumentation against Mary's perpetual virginity is extra-Scriptural.
-Theo